diff --git a/Libraries/LibJS/AST.h b/Libraries/LibJS/AST.h
index 450351644c7..2c0b878a31a 100644
--- a/Libraries/LibJS/AST.h
+++ b/Libraries/LibJS/AST.h
@@ -51,7 +51,7 @@ create_ast_node(SourceRange range, Args&&... args)
     return adopt_ref(*new T(move(range), forward<Args>(args)...));
 }
 
-class ASTNode : public RefCounted<ASTNode> {
+class JS_API ASTNode : public RefCounted<ASTNode> {
 public:
     virtual ~ASTNode() = default;
 
@@ -167,7 +167,7 @@ enum class DeclarationKind {
     Const,
 };
 
-class Statement : public ASTNode {
+class JS_API Statement : public ASTNode {
 public:
     explicit Statement(SourceRange source_range)
         : ASTNode(move(source_range))
@@ -182,7 +182,7 @@ private:
 };
 
 // 14.13 Labelled Statements, https://tc39.es/ecma262/#sec-labelled-statements
-class LabelledStatement final : public Statement {
+class JS_API LabelledStatement final : public Statement {
 public:
     LabelledStatement(SourceRange source_range, FlyString label, NonnullRefPtr<Statement const> labelled_item)
         : Statement(move(source_range))
@@ -206,7 +206,7 @@ private:
     NonnullRefPtr<Statement const> m_labelled_item;
 };
 
-class LabelableStatement : public Statement {
+class JS_API LabelableStatement : public Statement {
 public:
     using Statement::Statement;
 
@@ -217,7 +217,7 @@ protected:
     Vector<FlyString> m_labels;
 };
 
-class IterationStatement : public Statement {
+class JS_API IterationStatement : public Statement {
 public:
     using Statement::Statement;
 
@@ -227,7 +227,7 @@ private:
     virtual bool is_iteration_statement() const final { return true; }
 };
 
-class EmptyStatement final : public Statement {
+class JS_API EmptyStatement final : public Statement {
 public:
     explicit EmptyStatement(SourceRange source_range)
         : Statement(move(source_range))
@@ -236,7 +236,7 @@ public:
     virtual Bytecode::CodeGenerationErrorOr<Optional<Bytecode::ScopedOperand>> generate_bytecode(Bytecode::Generator&, Optional<Bytecode::ScopedOperand> preferred_dst = {}) const override;
 };
 
-class ErrorStatement final : public Statement {
+class JS_API ErrorStatement final : public Statement {
 public:
     explicit ErrorStatement(SourceRange source_range)
         : Statement(move(source_range))
@@ -244,7 +244,7 @@ public:
     }
 };
 
-class ExpressionStatement final : public Statement {
+class JS_API ExpressionStatement final : public Statement {
 public:
     ExpressionStatement(SourceRange source_range, NonnullRefPtr<Expression const> expression)
         : Statement(move(source_range))
@@ -292,7 +292,7 @@ public:
     }
 };
 
-class ScopeNode : public Statement {
+class JS_API ScopeNode : public Statement {
 public:
     template<typename T, typename... Args>
     T& append(SourceRange range, Args&&... args)
@@ -368,7 +368,7 @@ private:
 };
 
 // ImportEntry Record, https://tc39.es/ecma262/#table-importentry-record-fields
-struct ImportEntry {
+struct JS_API ImportEntry {
     Optional<FlyString> import_name; // [[ImportName]]: stored string if Optional is not empty, NAMESPACE-OBJECT otherwise
     FlyString local_name;            // [[LocalName]]
 
@@ -391,7 +391,7 @@ private:
     ModuleRequest* m_module_request = nullptr; // [[ModuleRequest]]
 };
 
-class ImportStatement final : public Statement {
+class JS_API ImportStatement final : public Statement {
 public:
     explicit ImportStatement(SourceRange source_range, ModuleRequest from_module, Vector<ImportEntry> entries = {})
         : Statement(move(source_range))
@@ -482,7 +482,7 @@ public:
     }
 };
 
-class ExportStatement final : public Statement {
+class JS_API ExportStatement final : public Statement {
 public:
     static FlyString local_name_for_default;
 
@@ -528,7 +528,7 @@ private:
     Optional<ModuleRequest> m_module_request;
 };
 
-class Program final : public ScopeNode {
+class JS_API Program final : public ScopeNode {
 public:
     enum class Type {
         Script,
@@ -580,7 +580,7 @@ private:
     bool m_has_top_level_await { false };
 };
 
-class BlockStatement final : public ScopeNode {
+class JS_API BlockStatement final : public ScopeNode {
 public:
     explicit BlockStatement(SourceRange source_range)
         : ScopeNode(move(source_range))
@@ -591,7 +591,7 @@ private:
     virtual bool is_block_statement() const override { return true; }
 };
 
-class FunctionBody final : public ScopeNode {
+class JS_API FunctionBody final : public ScopeNode {
 public:
     explicit FunctionBody(SourceRange source_range)
         : ScopeNode(move(source_range))
@@ -608,7 +608,7 @@ private:
     bool m_in_strict_mode { false };
 };
 
-class Expression : public ASTNode {
+class JS_API Expression : public ASTNode {
 public:
     explicit Expression(SourceRange source_range)
         : ASTNode(move(source_range))
@@ -616,7 +616,7 @@ public:
     }
 };
 
-class Declaration : public Statement {
+class JS_API Declaration : public Statement {
 public:
     explicit Declaration(SourceRange source_range)
         : Statement(move(source_range))
@@ -631,7 +631,7 @@ public:
     virtual bool is_lexical_declaration() const { return false; }
 };
 
-class ErrorDeclaration final : public Declaration {
+class JS_API ErrorDeclaration final : public Declaration {
 public:
     explicit ErrorDeclaration(SourceRange source_range)
         : Declaration(move(source_range))
@@ -644,7 +644,7 @@ public:
     }
 };
 
-struct BindingPattern : RefCounted<BindingPattern> {
+struct JS_API BindingPattern : RefCounted<BindingPattern> {
     // This covers both BindingProperty and BindingElement, hence the more generic name
     struct BindingEntry {
         // If this entry represents a BindingElement, then name will be Empty
@@ -673,7 +673,7 @@ struct BindingPattern : RefCounted<BindingPattern> {
     Kind kind { Kind::Object };
 };
 
-class Identifier final : public Expression {
+class JS_API Identifier final : public Expression {
 public:
     explicit Identifier(SourceRange source_range, FlyString string)
         : Expression(move(source_range))
@@ -777,7 +777,7 @@ struct FunctionParsingInsights {
     bool might_need_arguments_object { false };
 };
 
-class FunctionNode {
+class JS_API FunctionNode {
 public:
     FlyString name() const { return m_name ? m_name->string() : ""_fly_string; }
     RefPtr<Identifier const> name_identifier() const { return m_name; }
@@ -824,7 +824,7 @@ private:
     mutable RefPtr<SharedFunctionInstanceData> m_shared_data;
 };
 
-class FunctionDeclaration final
+class JS_API FunctionDeclaration final
     : public Declaration
     , public FunctionNode {
 public:
@@ -854,7 +854,7 @@ private:
     bool m_is_hoisted { false };
 };
 
-class FunctionExpression final
+class JS_API FunctionExpression final
     : public Expression
     , public FunctionNode {
 public:
@@ -881,7 +881,7 @@ private:
     virtual bool is_function_expression() const override { return true; }
 };
 
-class ErrorExpression final : public Expression {
+class JS_API ErrorExpression final : public Expression {
 public:
     explicit ErrorExpression(SourceRange source_range)
         : Expression(move(source_range))
@@ -909,7 +909,7 @@ private:
     bool m_is_yield_from { false };
 };
 
-class AwaitExpression final : public Expression {
+class JS_API AwaitExpression final : public Expression {
 public:
     explicit AwaitExpression(SourceRange source_range, NonnullRefPtr<Expression const> argument)
         : Expression(move(source_range))
@@ -924,7 +924,7 @@ private:
     NonnullRefPtr<Expression const> m_argument;
 };
 
-class ReturnStatement final : public Statement {
+class JS_API ReturnStatement final : public Statement {
 public:
     explicit ReturnStatement(SourceRange source_range, RefPtr<Expression const> argument)
         : Statement(move(source_range))
@@ -941,7 +941,7 @@ private:
     RefPtr<Expression const> m_argument;
 };
 
-class IfStatement final : public Statement {
+class JS_API IfStatement final : public Statement {
 public:
     IfStatement(SourceRange source_range, NonnullRefPtr<Expression const> predicate, NonnullRefPtr<Statement const> consequent, RefPtr<Statement const> alternate)
         : Statement(move(source_range))
@@ -964,7 +964,7 @@ private:
     RefPtr<Statement const> m_alternate;
 };
 
-class WhileStatement final : public IterationStatement {
+class JS_API WhileStatement final : public IterationStatement {
 public:
     WhileStatement(SourceRange source_range, NonnullRefPtr<Expression const> test, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -985,7 +985,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class DoWhileStatement final : public IterationStatement {
+class JS_API DoWhileStatement final : public IterationStatement {
 public:
     DoWhileStatement(SourceRange source_range, NonnullRefPtr<Expression const> test, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -1006,7 +1006,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class WithStatement final : public Statement {
+class JS_API WithStatement final : public Statement {
 public:
     WithStatement(SourceRange source_range, NonnullRefPtr<Expression const> object, NonnullRefPtr<Statement const> body)
         : Statement(move(source_range))
@@ -1026,7 +1026,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class ForStatement final : public IterationStatement {
+class JS_API ForStatement final : public IterationStatement {
 public:
     ForStatement(SourceRange source_range, RefPtr<ASTNode const> init, RefPtr<Expression const> test, RefPtr<Expression const> update, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -1053,7 +1053,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class ForInStatement final : public IterationStatement {
+class JS_API ForInStatement final : public IterationStatement {
 public:
     ForInStatement(SourceRange source_range, Variant<NonnullRefPtr<ASTNode const>, NonnullRefPtr<BindingPattern const>> lhs, NonnullRefPtr<Expression const> rhs, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -1077,7 +1077,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class ForOfStatement final : public IterationStatement {
+class JS_API ForOfStatement final : public IterationStatement {
 public:
     ForOfStatement(SourceRange source_range, Variant<NonnullRefPtr<ASTNode const>, NonnullRefPtr<BindingPattern const>> lhs, NonnullRefPtr<Expression const> rhs, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -1101,7 +1101,7 @@ private:
     NonnullRefPtr<Statement const> m_body;
 };
 
-class ForAwaitOfStatement final : public IterationStatement {
+class JS_API ForAwaitOfStatement final : public IterationStatement {
 public:
     ForAwaitOfStatement(SourceRange source_range, Variant<NonnullRefPtr<ASTNode const>, NonnullRefPtr<BindingPattern const>> lhs, NonnullRefPtr<Expression const> rhs, NonnullRefPtr<Statement const> body)
         : IterationStatement(move(source_range))
@@ -1146,7 +1146,7 @@ enum class BinaryOp {
     InstanceOf,
 };
 
-class BinaryExpression final : public Expression {
+class JS_API BinaryExpression final : public Expression {
 public:
     BinaryExpression(SourceRange source_range, BinaryOp op, NonnullRefPtr<Expression const> lhs, NonnullRefPtr<Expression const> rhs)
         : Expression(move(source_range))
@@ -1171,7 +1171,7 @@ enum class LogicalOp {
     NullishCoalescing,
 };
 
-class LogicalExpression final : public Expression {
+class JS_API LogicalExpression final : public Expression {
 public:
     LogicalExpression(SourceRange source_range, LogicalOp op, NonnullRefPtr<Expression const> lhs, NonnullRefPtr<Expression const> rhs)
         : Expression(move(source_range))
@@ -1200,7 +1200,7 @@ enum class UnaryOp {
     Delete,
 };
 
-class UnaryExpression final : public Expression {
+class JS_API UnaryExpression final : public Expression {
 public:
     UnaryExpression(SourceRange source_range, UnaryOp op, NonnullRefPtr<Expression const> lhs)
         : Expression(move(source_range))
@@ -1217,7 +1217,7 @@ private:
     NonnullRefPtr<Expression const> m_lhs;
 };
 
-class SequenceExpression final : public Expression {
+class JS_API SequenceExpression final : public Expression {
 public:
     SequenceExpression(SourceRange source_range, Vector<NonnullRefPtr<Expression const>> expressions)
         : Expression(move(source_range))
@@ -1233,7 +1233,7 @@ private:
     Vector<NonnullRefPtr<Expression const>> m_expressions;
 };
 
-class PrimitiveLiteral : public Expression {
+class JS_API PrimitiveLiteral : public Expression {
 public:
     virtual Value value() const = 0;
 
@@ -1247,7 +1247,7 @@ private:
     virtual bool is_primitive_literal() const override { return true; }
 };
 
-class BooleanLiteral final : public PrimitiveLiteral {
+class JS_API BooleanLiteral final : public PrimitiveLiteral {
 public:
     explicit BooleanLiteral(SourceRange source_range, bool value)
         : PrimitiveLiteral(move(source_range))
@@ -1266,7 +1266,7 @@ private:
     bool m_value { false };
 };
 
-class NumericLiteral final : public PrimitiveLiteral {
+class JS_API NumericLiteral final : public PrimitiveLiteral {
 public:
     explicit NumericLiteral(SourceRange source_range, double value)
         : PrimitiveLiteral(move(source_range))
@@ -1285,7 +1285,7 @@ private:
     Value m_value;
 };
 
-class BigIntLiteral final : public Expression {
+class JS_API BigIntLiteral final : public Expression {
 public:
     explicit BigIntLiteral(SourceRange source_range, ByteString value)
         : Expression(move(source_range))
@@ -1300,7 +1300,7 @@ private:
     ByteString m_value;
 };
 
-class StringLiteral final : public Expression {
+class JS_API StringLiteral final : public Expression {
 public:
     explicit StringLiteral(SourceRange source_range, String value)
         : Expression(move(source_range))
@@ -1319,7 +1319,7 @@ private:
     String m_value;
 };
 
-class NullLiteral final : public PrimitiveLiteral {
+class JS_API NullLiteral final : public PrimitiveLiteral {
 public:
     explicit NullLiteral(SourceRange source_range)
         : PrimitiveLiteral(move(source_range))
@@ -1335,7 +1335,7 @@ private:
     virtual bool is_null_literal() const override { return true; }
 };
 
-class RegExpLiteral final : public Expression {
+class JS_API RegExpLiteral final : public Expression {
 public:
     RegExpLiteral(SourceRange source_range, regex::Parser::Result parsed_regex, String parsed_pattern, regex::RegexOptions<ECMAScriptFlags> parsed_flags, String pattern, String flags)
         : Expression(move(source_range))
@@ -1364,7 +1364,7 @@ private:
     String m_flags;
 };
 
-class PrivateIdentifier final : public Expression {
+class JS_API PrivateIdentifier final : public Expression {
 public:
     explicit PrivateIdentifier(SourceRange source_range, FlyString string)
         : Expression(move(source_range))
@@ -1382,7 +1382,7 @@ private:
     FlyString m_string;
 };
 
-class ClassElement : public ASTNode {
+class JS_API ClassElement : public ASTNode {
 public:
     ClassElement(SourceRange source_range, bool is_static)
         : ASTNode(move(source_range))
@@ -1409,7 +1409,7 @@ private:
     bool m_is_static { false };
 };
 
-class ClassMethod final : public ClassElement {
+class JS_API ClassMethod final : public ClassElement {
 public:
     enum class Kind {
         Method,
@@ -1440,7 +1440,7 @@ private:
     Kind m_kind;
 };
 
-class ClassField final : public ClassElement {
+class JS_API ClassField final : public ClassElement {
 public:
     ClassField(SourceRange source_range, NonnullRefPtr<Expression const> key, RefPtr<Expression const> init, bool is_static)
         : ClassElement(move(source_range), is_static)
@@ -1464,7 +1464,7 @@ private:
     RefPtr<Expression const> m_initializer;
 };
 
-class StaticInitializer final : public ClassElement {
+class JS_API StaticInitializer final : public ClassElement {
 public:
     StaticInitializer(SourceRange source_range, NonnullRefPtr<FunctionBody> function_body)
         : ClassElement(move(source_range), true)
@@ -1481,7 +1481,7 @@ private:
     NonnullRefPtr<FunctionBody> m_function_body;
 };
 
-class SuperExpression final : public Expression {
+class JS_API SuperExpression final : public Expression {
 public:
     explicit SuperExpression(SourceRange source_range)
         : Expression(move(source_range))
@@ -1494,7 +1494,7 @@ public:
     virtual bool is_super_expression() const override { return true; }
 };
 
-class ClassExpression final : public Expression {
+class JS_API ClassExpression final : public Expression {
 public:
     ClassExpression(SourceRange source_range, RefPtr<Identifier const> name, ByteString source_text, RefPtr<FunctionExpression const> constructor, RefPtr<Expression const> super_class, Vector<NonnullRefPtr<ClassElement const>> elements)
         : Expression(move(source_range))
@@ -1531,7 +1531,7 @@ private:
     Vector<NonnullRefPtr<ClassElement const>> m_elements;
 };
 
-class ClassDeclaration final : public Declaration {
+class JS_API ClassDeclaration final : public Declaration {
 public:
     ClassDeclaration(SourceRange source_range, NonnullRefPtr<ClassExpression const> class_expression)
         : Declaration(move(source_range))
@@ -1558,7 +1558,7 @@ private:
 
 // We use this class to mimic  Initializer : = AssignmentExpression of
 // 10.2.1.3 Runtime Semantics: EvaluateBody, https://tc39.es/ecma262/#sec-runtime-semantics-evaluatebody
-class ClassFieldInitializerStatement final : public Statement {
+class JS_API ClassFieldInitializerStatement final : public Statement {
 public:
     ClassFieldInitializerStatement(SourceRange source_range, NonnullRefPtr<Expression const> expression, FlyString field_name)
         : Statement(move(source_range))
@@ -1575,7 +1575,7 @@ private:
     FlyString m_class_field_identifier_name; // [[ClassFieldIdentifierName]]
 };
 
-class SpreadExpression final : public Expression {
+class JS_API SpreadExpression final : public Expression {
 public:
     explicit SpreadExpression(SourceRange source_range, NonnullRefPtr<Expression const> target)
         : Expression(move(source_range))
@@ -1592,7 +1592,7 @@ private:
     NonnullRefPtr<Expression const> m_target;
 };
 
-class ThisExpression final : public Expression {
+class JS_API ThisExpression final : public Expression {
 public:
     explicit ThisExpression(SourceRange source_range)
         : Expression(move(source_range))
@@ -1617,7 +1617,7 @@ enum InsideParenthesesEnum {
     NotInsideParentheses,
 };
 
-class CallExpression : public ASTNodeWithTailArray<CallExpression, Expression, CallExpressionArgument> {
+class JS_API CallExpression : public ASTNodeWithTailArray<CallExpression, Expression, CallExpressionArgument> {
     friend class ASTNodeWithTailArray;
 
     InvocationStyleEnum m_invocation_style;
@@ -1655,7 +1655,7 @@ protected:
     NonnullRefPtr<Expression const> m_callee;
 };
 
-class NewExpression final : public CallExpression {
+class JS_API NewExpression final : public CallExpression {
     friend class ASTNodeWithTailArray;
 
 public:
@@ -1672,7 +1672,7 @@ private:
 
 static_assert(sizeof(NewExpression) == sizeof(CallExpression), "Adding members to NewExpression will break CallExpression memory layout");
 
-class SuperCall final : public Expression {
+class JS_API SuperCall final : public Expression {
 public:
     // This is here to be able to make a constructor like
     // constructor(...args) { super(...args); } which does not use @@iterator of %Array.prototype%.
@@ -1723,7 +1723,7 @@ enum class AssignmentOp {
     NullishAssignment,
 };
 
-class AssignmentExpression final : public Expression {
+class JS_API AssignmentExpression final : public Expression {
 public:
     AssignmentExpression(SourceRange source_range, AssignmentOp op, NonnullRefPtr<Expression const> lhs, NonnullRefPtr<Expression const> rhs)
         : Expression(move(source_range))
@@ -1755,7 +1755,7 @@ enum class UpdateOp {
     Decrement,
 };
 
-class UpdateExpression final : public Expression {
+class JS_API UpdateExpression final : public Expression {
 public:
     UpdateExpression(SourceRange source_range, UpdateOp op, NonnullRefPtr<Expression const> argument, bool prefixed = false)
         : Expression(move(source_range))
@@ -1776,7 +1776,7 @@ private:
     bool m_prefixed;
 };
 
-class VariableDeclarator final : public ASTNode {
+class JS_API VariableDeclarator final : public ASTNode {
 public:
     VariableDeclarator(SourceRange source_range, NonnullRefPtr<Identifier const> id)
         : ASTNode(move(source_range))
@@ -1808,7 +1808,7 @@ private:
     RefPtr<Expression const> m_init;
 };
 
-class VariableDeclaration final : public Declaration {
+class JS_API VariableDeclaration final : public Declaration {
 public:
     VariableDeclaration(SourceRange source_range, DeclarationKind declaration_kind, Vector<NonnullRefPtr<VariableDeclarator const>> declarations)
         : Declaration(move(source_range))
@@ -1837,7 +1837,7 @@ private:
     Vector<NonnullRefPtr<VariableDeclarator const>> m_declarations;
 };
 
-class UsingDeclaration final : public Declaration {
+class JS_API UsingDeclaration final : public Declaration {
 public:
     UsingDeclaration(SourceRange source_range, Vector<NonnullRefPtr<VariableDeclarator const>> declarations)
         : Declaration(move(source_range))
@@ -1859,7 +1859,7 @@ private:
     Vector<NonnullRefPtr<VariableDeclarator const>> m_declarations;
 };
 
-class ObjectProperty final : public ASTNode {
+class JS_API ObjectProperty final : public ASTNode {
 public:
     enum class Type : u8 {
         KeyValue,
@@ -1897,7 +1897,7 @@ private:
     RefPtr<Expression const> m_value;
 };
 
-class ObjectExpression final : public Expression {
+class JS_API ObjectExpression final : public Expression {
 public:
     explicit ObjectExpression(SourceRange source_range, Vector<NonnullRefPtr<ObjectProperty>> properties = {})
         : Expression(move(source_range))
@@ -1914,7 +1914,7 @@ private:
     Vector<NonnullRefPtr<ObjectProperty>> m_properties;
 };
 
-class ArrayExpression final : public Expression {
+class JS_API ArrayExpression final : public Expression {
 public:
     ArrayExpression(SourceRange source_range, Vector<RefPtr<Expression const>> elements)
         : Expression(move(source_range))
@@ -1933,7 +1933,7 @@ private:
     Vector<RefPtr<Expression const>> m_elements;
 };
 
-class TemplateLiteral final : public Expression {
+class JS_API TemplateLiteral final : public Expression {
 public:
     TemplateLiteral(SourceRange source_range, Vector<NonnullRefPtr<Expression const>> expressions)
         : Expression(move(source_range))
@@ -1959,7 +1959,7 @@ private:
     Vector<NonnullRefPtr<Expression const>> const m_raw_strings;
 };
 
-class TaggedTemplateLiteral final : public Expression {
+class JS_API TaggedTemplateLiteral final : public Expression {
 public:
     TaggedTemplateLiteral(SourceRange source_range, NonnullRefPtr<Expression const> tag, NonnullRefPtr<TemplateLiteral const> template_literal)
         : Expression(move(source_range))
@@ -1976,7 +1976,7 @@ private:
     NonnullRefPtr<TemplateLiteral const> const m_template_literal;
 };
 
-class MemberExpression final : public Expression {
+class JS_API MemberExpression final : public Expression {
 public:
     MemberExpression(SourceRange source_range, NonnullRefPtr<Expression const> object, NonnullRefPtr<Expression const> property, bool computed = false)
         : Expression(move(source_range))
@@ -2005,7 +2005,7 @@ private:
     NonnullRefPtr<Expression const> m_property;
 };
 
-class OptionalChain final : public Expression {
+class JS_API OptionalChain final : public Expression {
 public:
     enum class Mode {
         Optional,
@@ -2051,7 +2051,7 @@ private:
     Vector<Reference> m_references;
 };
 
-class MetaProperty final : public Expression {
+class JS_API MetaProperty final : public Expression {
 public:
     enum class Type {
         NewTarget,
@@ -2071,7 +2071,7 @@ private:
     Type m_type;
 };
 
-class ImportCall final : public Expression {
+class JS_API ImportCall final : public Expression {
 public:
     ImportCall(SourceRange source_range, NonnullRefPtr<Expression const> specifier, RefPtr<Expression const> options)
         : Expression(move(source_range))
@@ -2090,7 +2090,7 @@ private:
     RefPtr<Expression const> m_options;
 };
 
-class ConditionalExpression final : public Expression {
+class JS_API ConditionalExpression final : public Expression {
 public:
     ConditionalExpression(SourceRange source_range, NonnullRefPtr<Expression const> test, NonnullRefPtr<Expression const> consequent, NonnullRefPtr<Expression const> alternate)
         : Expression(move(source_range))
@@ -2109,7 +2109,7 @@ private:
     NonnullRefPtr<Expression const> m_alternate;
 };
 
-class CatchClause final : public ASTNode {
+class JS_API CatchClause final : public ASTNode {
 public:
     CatchClause(SourceRange source_range, NonnullRefPtr<Identifier const> parameter, NonnullRefPtr<BlockStatement const> body)
         : ASTNode(move(source_range))
@@ -2142,7 +2142,7 @@ private:
     NonnullRefPtr<BlockStatement const> m_body;
 };
 
-class TryStatement final : public Statement {
+class JS_API TryStatement final : public Statement {
 public:
     TryStatement(SourceRange source_range, NonnullRefPtr<BlockStatement const> block, RefPtr<CatchClause const> handler, RefPtr<BlockStatement const> finalizer)
         : Statement(move(source_range))
@@ -2165,7 +2165,7 @@ private:
     RefPtr<BlockStatement const> m_finalizer;
 };
 
-class ThrowStatement final : public Statement {
+class JS_API ThrowStatement final : public Statement {
 public:
     explicit ThrowStatement(SourceRange source_range, NonnullRefPtr<Expression const> argument)
         : Statement(move(source_range))
@@ -2182,7 +2182,7 @@ private:
     NonnullRefPtr<Expression const> m_argument;
 };
 
-class SwitchCase final : public ScopeNode {
+class JS_API SwitchCase final : public ScopeNode {
 public:
     SwitchCase(SourceRange source_range, RefPtr<Expression const> test)
         : ScopeNode(move(source_range))
@@ -2198,7 +2198,7 @@ private:
     RefPtr<Expression const> m_test;
 };
 
-class SwitchStatement final : public ScopeNode {
+class JS_API SwitchStatement final : public ScopeNode {
 public:
     SwitchStatement(SourceRange source_range, NonnullRefPtr<Expression const> discriminant)
         : ScopeNode(move(source_range))
@@ -2217,7 +2217,7 @@ private:
     Vector<NonnullRefPtr<SwitchCase const>> m_cases;
 };
 
-class BreakStatement final : public Statement {
+class JS_API BreakStatement final : public Statement {
 public:
     BreakStatement(SourceRange source_range, Optional<FlyString> target_label)
         : Statement(move(source_range))
@@ -2232,7 +2232,7 @@ private:
     Optional<FlyString> m_target_label;
 };
 
-class ContinueStatement final : public Statement {
+class JS_API ContinueStatement final : public Statement {
 public:
     ContinueStatement(SourceRange source_range, Optional<FlyString> target_label)
         : Statement(move(source_range))
@@ -2248,7 +2248,7 @@ private:
     Optional<FlyString> m_target_label;
 };
 
-class DebuggerStatement final : public Statement {
+class JS_API DebuggerStatement final : public Statement {
 public:
     explicit DebuggerStatement(SourceRange source_range)
         : Statement(move(source_range))
@@ -2258,7 +2258,7 @@ public:
     virtual Bytecode::CodeGenerationErrorOr<Optional<Bytecode::ScopedOperand>> generate_bytecode(Bytecode::Generator&, Optional<Bytecode::ScopedOperand> preferred_dst = {}) const override;
 };
 
-class SyntheticReferenceExpression final : public Expression {
+class JS_API SyntheticReferenceExpression final : public Expression {
 public:
     explicit SyntheticReferenceExpression(SourceRange source_range, Reference reference, Value value)
         : Expression(move(source_range))
diff --git a/Libraries/LibJS/Bytecode/BasicBlock.h b/Libraries/LibJS/Bytecode/BasicBlock.h
index d9e0ff4bf87..4315aa65ee9 100644
--- a/Libraries/LibJS/Bytecode/BasicBlock.h
+++ b/Libraries/LibJS/Bytecode/BasicBlock.h
@@ -22,7 +22,7 @@ struct UnwindInfo {
     bool handler_called { false };
 };
 
-class BasicBlock {
+class JS_API BasicBlock {
     AK_MAKE_NONCOPYABLE(BasicBlock);
 
 public:
diff --git a/Libraries/LibJS/Bytecode/CodeGenerationError.h b/Libraries/LibJS/Bytecode/CodeGenerationError.h
index 5e23d71e09c..1f6e77080c6 100644
--- a/Libraries/LibJS/Bytecode/CodeGenerationError.h
+++ b/Libraries/LibJS/Bytecode/CodeGenerationError.h
@@ -13,7 +13,7 @@
 
 namespace JS::Bytecode {
 
-struct CodeGenerationError {
+struct JS_API CodeGenerationError {
     ASTNode const* failing_node { nullptr };
     StringView reason_literal;
 
diff --git a/Libraries/LibJS/Bytecode/Executable.h b/Libraries/LibJS/Bytecode/Executable.h
index ecffacf1df4..327f5ae5526 100644
--- a/Libraries/LibJS/Bytecode/Executable.h
+++ b/Libraries/LibJS/Bytecode/Executable.h
@@ -47,7 +47,7 @@ struct SourceRecord {
     u32 source_end_offset {};
 };
 
-class Executable final : public Cell {
+class JS_API Executable final : public Cell {
     GC_CELL(Executable, Cell);
     GC_DECLARE_ALLOCATOR(Executable);
 
diff --git a/Libraries/LibJS/Bytecode/Generator.h b/Libraries/LibJS/Bytecode/Generator.h
index e0cb070ac7d..a0d37b5daa6 100644
--- a/Libraries/LibJS/Bytecode/Generator.h
+++ b/Libraries/LibJS/Bytecode/Generator.h
@@ -23,7 +23,7 @@
 
 namespace JS::Bytecode {
 
-class Generator {
+class JS_API Generator {
 public:
     VM& vm() { return m_vm; }
 
@@ -55,7 +55,7 @@ public:
     [[nodiscard]] bool is_local_initialized(Identifier::Local const&) const;
     [[nodiscard]] bool is_local_lexically_declared(Identifier::Local const& local) const;
 
-    class SourceLocationScope {
+    class JS_API SourceLocationScope {
     public:
         SourceLocationScope(Generator&, ASTNode const& node);
         ~SourceLocationScope();
@@ -65,7 +65,7 @@ public:
         ASTNode const* m_previous_node { nullptr };
     };
 
-    class UnwindContext {
+    class JS_API UnwindContext {
     public:
         UnwindContext(Generator&, Optional<Label> finalizer);
 
diff --git a/Libraries/LibJS/Bytecode/IdentifierTable.h b/Libraries/LibJS/Bytecode/IdentifierTable.h
index 5c1f1703ca0..b242a54ee7c 100644
--- a/Libraries/LibJS/Bytecode/IdentifierTable.h
+++ b/Libraries/LibJS/Bytecode/IdentifierTable.h
@@ -9,6 +9,7 @@
 #include <AK/DistinctNumeric.h>
 #include <AK/FlyString.h>
 #include <AK/Vector.h>
+#include <LibJS/Forward.h>
 
 namespace JS::Bytecode {
 
@@ -18,7 +19,7 @@ struct IdentifierTableIndex {
     u32 value { 0 };
 };
 
-class IdentifierTable {
+class JS_API IdentifierTable {
     AK_MAKE_NONMOVABLE(IdentifierTable);
     AK_MAKE_NONCOPYABLE(IdentifierTable);
 
diff --git a/Libraries/LibJS/Bytecode/Instruction.h b/Libraries/LibJS/Bytecode/Instruction.h
index 045b79d57f6..55f0324e0db 100644
--- a/Libraries/LibJS/Bytecode/Instruction.h
+++ b/Libraries/LibJS/Bytecode/Instruction.h
@@ -153,7 +153,7 @@
 
 namespace JS::Bytecode {
 
-class alignas(void*) Instruction {
+class alignas(void*) JS_API Instruction {
 public:
     constexpr static bool IsTerminator = false;
     static constexpr bool IsVariableLength = false;
@@ -185,7 +185,7 @@ private:
     Type m_type {};
 };
 
-class InstructionStreamIterator {
+class JS_API InstructionStreamIterator {
 public:
     InstructionStreamIterator(ReadonlyBytes bytes, Executable const* executable = nullptr, size_t offset = 0)
         : m_begin(bytes.data())
diff --git a/Libraries/LibJS/Bytecode/Interpreter.h b/Libraries/LibJS/Bytecode/Interpreter.h
index 385cd650f6b..1dfff670877 100644
--- a/Libraries/LibJS/Bytecode/Interpreter.h
+++ b/Libraries/LibJS/Bytecode/Interpreter.h
@@ -19,7 +19,7 @@ namespace JS::Bytecode {
 
 class InstructionStreamIterator;
 
-class Interpreter {
+class JS_API Interpreter {
 public:
     explicit Interpreter(VM&);
     ~Interpreter();
diff --git a/Libraries/LibJS/Bytecode/Label.h b/Libraries/LibJS/Bytecode/Label.h
index 9536458ca01..a1433d88338 100644
--- a/Libraries/LibJS/Bytecode/Label.h
+++ b/Libraries/LibJS/Bytecode/Label.h
@@ -7,12 +7,13 @@
 #pragma once
 
 #include <AK/Format.h>
+#include <LibJS/Forward.h>
 
 namespace JS::Bytecode {
 
 class BasicBlock;
 
-class Label {
+class JS_API Label {
 public:
     explicit Label(BasicBlock const&);
 
diff --git a/Libraries/LibJS/Bytecode/Op.h b/Libraries/LibJS/Bytecode/Op.h
index 479fce53a60..9d3cb914bdb 100644
--- a/Libraries/LibJS/Bytecode/Op.h
+++ b/Libraries/LibJS/Bytecode/Op.h
@@ -34,7 +34,7 @@ class FunctionExpression;
 
 namespace JS::Bytecode::Op {
 
-class CreateRestParams final : public Instruction {
+class JS_API CreateRestParams final : public Instruction {
 public:
     CreateRestParams(Operand dst, u32 rest_index)
         : Instruction(Type::CreateRestParams)
@@ -55,7 +55,7 @@ private:
     u32 m_rest_index;
 };
 
-class CreateArguments final : public Instruction {
+class JS_API CreateArguments final : public Instruction {
 public:
     enum class Kind {
         Mapped,
@@ -84,7 +84,7 @@ private:
     bool m_is_immutable { false };
 };
 
-class Mov final : public Instruction {
+class JS_API Mov final : public Instruction {
 public:
     Mov(Operand dst, Operand src)
         : Instruction(Type::Mov)
@@ -135,7 +135,7 @@ private:
     O(StrictlyEquals, strict_equals)
 
 #define JS_DECLARE_COMMON_BINARY_OP(OpTitleCase, op_snake_case)             \
-    class OpTitleCase final : public Instruction {                          \
+    class JS_API OpTitleCase final : public Instruction {                   \
     public:                                                                 \
         explicit OpTitleCase(Operand dst, Operand lhs, Operand rhs)         \
             : Instruction(Type::OpTitleCase)                                \
@@ -176,7 +176,7 @@ JS_ENUMERATE_COMMON_BINARY_OPS_WITH_FAST_PATH(JS_DECLARE_COMMON_BINARY_OP)
     O(Typeof, typeof_)
 
 #define JS_DECLARE_COMMON_UNARY_OP(OpTitleCase, op_snake_case)              \
-    class OpTitleCase final : public Instruction {                          \
+    class JS_API OpTitleCase final : public Instruction {                   \
     public:                                                                 \
         OpTitleCase(Operand dst, Operand src)                               \
             : Instruction(Type::OpTitleCase)                                \
@@ -204,7 +204,7 @@ JS_ENUMERATE_COMMON_BINARY_OPS_WITH_FAST_PATH(JS_DECLARE_COMMON_BINARY_OP)
 JS_ENUMERATE_COMMON_UNARY_OPS(JS_DECLARE_COMMON_UNARY_OP)
 #undef JS_DECLARE_COMMON_UNARY_OP
 
-class NewObject final : public Instruction {
+class JS_API NewObject final : public Instruction {
 public:
     explicit NewObject(Operand dst)
         : Instruction(Type::NewObject)
@@ -225,7 +225,7 @@ private:
     Operand m_dst;
 };
 
-class NewRegExp final : public Instruction {
+class JS_API NewRegExp final : public Instruction {
 public:
     NewRegExp(Operand dst, StringTableIndex source_index, StringTableIndex flags_index, RegexTableIndex regex_index)
         : Instruction(Type::NewRegExp)
@@ -259,7 +259,7 @@ private:
     O(TypeError)
 
 #define JS_DECLARE_NEW_BUILTIN_ERROR_OP(ErrorName)                         \
-    class New##ErrorName final : public Instruction {                      \
+    class JS_API New##ErrorName final : public Instruction {               \
     public:                                                                \
         New##ErrorName(Operand dst, StringTableIndex error_string)         \
             : Instruction(Type::New##ErrorName)                            \
@@ -287,7 +287,7 @@ JS_ENUMERATE_NEW_BUILTIN_ERROR_OPS(JS_DECLARE_NEW_BUILTIN_ERROR_OP)
 #undef JS_DECLARE_NEW_BUILTIN_ERROR_OP
 
 // NOTE: This instruction is variable-width depending on the number of excluded names
-class CopyObjectExcludingProperties final : public Instruction {
+class JS_API CopyObjectExcludingProperties final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -330,7 +330,7 @@ private:
 };
 
 // NOTE: This instruction is variable-width depending on the number of elements!
-class NewArray final : public Instruction {
+class JS_API NewArray final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -375,7 +375,7 @@ private:
     Operand m_elements[];
 };
 
-class NewPrimitiveArray final : public Instruction {
+class JS_API NewPrimitiveArray final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -410,7 +410,7 @@ private:
     Value m_elements[];
 };
 
-class AddPrivateName final : public Instruction {
+class JS_API AddPrivateName final : public Instruction {
 public:
     explicit AddPrivateName(IdentifierTableIndex name)
         : Instruction(Type::AddPrivateName)
@@ -425,7 +425,7 @@ private:
     IdentifierTableIndex m_name;
 };
 
-class ArrayAppend final : public Instruction {
+class JS_API ArrayAppend final : public Instruction {
 public:
     ArrayAppend(Operand dst, Operand src, bool is_spread)
         : Instruction(Type::ArrayAppend)
@@ -453,7 +453,7 @@ private:
     bool m_is_spread = false;
 };
 
-class ImportCall final : public Instruction {
+class JS_API ImportCall final : public Instruction {
 public:
     ImportCall(Operand dst, Operand specifier, Operand options)
         : Instruction(Type::ImportCall)
@@ -482,7 +482,7 @@ private:
     Operand m_options;
 };
 
-class IteratorToArray final : public Instruction {
+class JS_API IteratorToArray final : public Instruction {
 public:
     explicit IteratorToArray(Operand dst, Operand iterator)
         : Instruction(Type::IteratorToArray)
@@ -508,7 +508,7 @@ private:
     Operand m_iterator;
 };
 
-class ConcatString final : public Instruction {
+class JS_API ConcatString final : public Instruction {
 public:
     explicit ConcatString(Operand dst, Operand src)
         : Instruction(Type::ConcatString)
@@ -544,7 +544,7 @@ enum class BindingInitializationMode {
     Set,
 };
 
-class CreateLexicalEnvironment final : public Instruction {
+class JS_API CreateLexicalEnvironment final : public Instruction {
 public:
     explicit CreateLexicalEnvironment(u32 capacity = 0)
         : Instruction(Type::CreateLexicalEnvironment)
@@ -559,7 +559,7 @@ private:
     u32 m_capacity { 0 };
 };
 
-class CreateVariableEnvironment final : public Instruction {
+class JS_API CreateVariableEnvironment final : public Instruction {
 public:
     explicit CreateVariableEnvironment(u32 capacity = 0)
         : Instruction(Type::CreateVariableEnvironment)
@@ -574,7 +574,7 @@ private:
     u32 m_capacity { 0 };
 };
 
-class CreatePrivateEnvironment final : public Instruction {
+class JS_API CreatePrivateEnvironment final : public Instruction {
 public:
     explicit CreatePrivateEnvironment()
         : Instruction(Type::CreatePrivateEnvironment)
@@ -585,7 +585,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class EnterObjectEnvironment final : public Instruction {
+class JS_API EnterObjectEnvironment final : public Instruction {
 public:
     explicit EnterObjectEnvironment(Operand object)
         : Instruction(Type::EnterObjectEnvironment)
@@ -607,7 +607,7 @@ private:
     Operand m_object;
 };
 
-class Catch final : public Instruction {
+class JS_API Catch final : public Instruction {
 public:
     explicit Catch(Operand dst)
         : Instruction(Type::Catch)
@@ -629,7 +629,7 @@ private:
     Operand m_dst;
 };
 
-class LeaveFinally final : public Instruction {
+class JS_API LeaveFinally final : public Instruction {
 public:
     explicit LeaveFinally()
         : Instruction(Type::LeaveFinally)
@@ -640,7 +640,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class RestoreScheduledJump final : public Instruction {
+class JS_API RestoreScheduledJump final : public Instruction {
 public:
     explicit RestoreScheduledJump()
         : Instruction(Type::RestoreScheduledJump)
@@ -651,7 +651,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class CreateVariable final : public Instruction {
+class JS_API CreateVariable final : public Instruction {
 public:
     explicit CreateVariable(IdentifierTableIndex identifier, EnvironmentMode mode, bool is_immutable, bool is_global = false, bool is_strict = false)
         : Instruction(Type::CreateVariable)
@@ -680,7 +680,7 @@ private:
     bool m_is_strict { false };
 };
 
-class InitializeLexicalBinding final : public Instruction {
+class JS_API InitializeLexicalBinding final : public Instruction {
 public:
     explicit InitializeLexicalBinding(IdentifierTableIndex identifier, Operand src)
         : Instruction(Type::InitializeLexicalBinding)
@@ -705,7 +705,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class InitializeVariableBinding final : public Instruction {
+class JS_API InitializeVariableBinding final : public Instruction {
 public:
     explicit InitializeVariableBinding(IdentifierTableIndex identifier, Operand src)
         : Instruction(Type::InitializeVariableBinding)
@@ -730,7 +730,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class SetLexicalBinding final : public Instruction {
+class JS_API SetLexicalBinding final : public Instruction {
 public:
     explicit SetLexicalBinding(IdentifierTableIndex identifier, Operand src)
         : Instruction(Type::SetLexicalBinding)
@@ -755,7 +755,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class SetVariableBinding final : public Instruction {
+class JS_API SetVariableBinding final : public Instruction {
 public:
     explicit SetVariableBinding(IdentifierTableIndex identifier, Operand src)
         : Instruction(Type::SetVariableBinding)
@@ -780,7 +780,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class GetCalleeAndThisFromEnvironment final : public Instruction {
+class JS_API GetCalleeAndThisFromEnvironment final : public Instruction {
 public:
     explicit GetCalleeAndThisFromEnvironment(Operand callee, Operand this_value, IdentifierTableIndex identifier)
         : Instruction(Type::GetCalleeAndThisFromEnvironment)
@@ -809,7 +809,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class GetBinding final : public Instruction {
+class JS_API GetBinding final : public Instruction {
 public:
     explicit GetBinding(Operand dst, IdentifierTableIndex identifier)
         : Instruction(Type::GetBinding)
@@ -835,7 +835,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class GetInitializedBinding final : public Instruction {
+class JS_API GetInitializedBinding final : public Instruction {
 public:
     explicit GetInitializedBinding(Operand dst, IdentifierTableIndex identifier)
         : Instruction(Type::GetInitializedBinding)
@@ -861,7 +861,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class GetGlobal final : public Instruction {
+class JS_API GetGlobal final : public Instruction {
 public:
     GetGlobal(Operand dst, IdentifierTableIndex identifier, u32 cache_index)
         : Instruction(Type::GetGlobal)
@@ -889,7 +889,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class SetGlobal final : public Instruction {
+class JS_API SetGlobal final : public Instruction {
 public:
     SetGlobal(IdentifierTableIndex identifier, Operand src, u32 cache_index)
         : Instruction(Type::SetGlobal)
@@ -917,7 +917,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class DeleteVariable final : public Instruction {
+class JS_API DeleteVariable final : public Instruction {
 public:
     explicit DeleteVariable(Operand dst, IdentifierTableIndex identifier)
         : Instruction(Type::DeleteVariable)
@@ -942,7 +942,7 @@ private:
     IdentifierTableIndex m_identifier;
 };
 
-class GetById final : public Instruction {
+class JS_API GetById final : public Instruction {
 public:
     GetById(Operand dst, Operand base, IdentifierTableIndex property, Optional<IdentifierTableIndex> base_identifier, u32 cache_index)
         : Instruction(Type::GetById)
@@ -975,7 +975,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class GetCompletionFields final : public Instruction {
+class JS_API GetCompletionFields final : public Instruction {
 public:
     GetCompletionFields(Operand type_dst, Operand value_dst, Operand completion)
         : Instruction(Type::GetCompletionFields)
@@ -1004,7 +1004,7 @@ private:
     Operand m_completion;
 };
 
-class SetCompletionType final : public Instruction {
+class JS_API SetCompletionType final : public Instruction {
 public:
     SetCompletionType(Operand completion, Completion::Type type)
         : Instruction(Type::SetCompletionType)
@@ -1027,7 +1027,7 @@ private:
     Completion::Type m_type;
 };
 
-class GetByIdWithThis final : public Instruction {
+class JS_API GetByIdWithThis final : public Instruction {
 public:
     GetByIdWithThis(Operand dst, Operand base, IdentifierTableIndex property, Operand this_value, u32 cache_index)
         : Instruction(Type::GetByIdWithThis)
@@ -1062,7 +1062,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class GetLength final : public Instruction {
+class JS_API GetLength final : public Instruction {
 public:
     GetLength(Operand dst, Operand base, Optional<IdentifierTableIndex> base_identifier, u32 cache_index)
         : Instruction(Type::GetLength)
@@ -1092,7 +1092,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class GetLengthWithThis final : public Instruction {
+class JS_API GetLengthWithThis final : public Instruction {
 public:
     GetLengthWithThis(Operand dst, Operand base, Operand this_value, u32 cache_index)
         : Instruction(Type::GetLengthWithThis)
@@ -1124,7 +1124,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class GetPrivateById final : public Instruction {
+class JS_API GetPrivateById final : public Instruction {
 public:
     explicit GetPrivateById(Operand dst, Operand base, IdentifierTableIndex property)
         : Instruction(Type::GetPrivateById)
@@ -1152,7 +1152,7 @@ private:
     IdentifierTableIndex m_property;
 };
 
-class HasPrivateId final : public Instruction {
+class JS_API HasPrivateId final : public Instruction {
 public:
     HasPrivateId(Operand dst, Operand base, IdentifierTableIndex property)
         : Instruction(Type::HasPrivateId)
@@ -1188,7 +1188,7 @@ enum class PropertyKind {
     ProtoSetter,
 };
 
-class PutBySpread final : public Instruction {
+class JS_API PutBySpread final : public Instruction {
 public:
     PutBySpread(Operand base, Operand src)
         : Instruction(Type::PutBySpread)
@@ -1213,7 +1213,7 @@ private:
     Operand m_src;
 };
 
-class PutById final : public Instruction {
+class JS_API PutById final : public Instruction {
 public:
     explicit PutById(Operand base, IdentifierTableIndex property, Operand src, PropertyKind kind, u32 cache_index, Optional<IdentifierTableIndex> base_identifier = {})
         : Instruction(Type::PutById)
@@ -1249,7 +1249,7 @@ private:
     Optional<IdentifierTableIndex> m_base_identifier {};
 };
 
-class PutByIdWithThis final : public Instruction {
+class JS_API PutByIdWithThis final : public Instruction {
 public:
     PutByIdWithThis(Operand base, Operand this_value, IdentifierTableIndex property, Operand src, PropertyKind kind, u32 cache_index)
         : Instruction(Type::PutByIdWithThis)
@@ -1287,7 +1287,7 @@ private:
     u32 m_cache_index { 0 };
 };
 
-class PutPrivateById final : public Instruction {
+class JS_API PutPrivateById final : public Instruction {
 public:
     explicit PutPrivateById(Operand base, IdentifierTableIndex property, Operand src, PropertyKind kind = PropertyKind::KeyValue)
         : Instruction(Type::PutPrivateById)
@@ -1317,7 +1317,7 @@ private:
     PropertyKind m_kind;
 };
 
-class DeleteById final : public Instruction {
+class JS_API DeleteById final : public Instruction {
 public:
     explicit DeleteById(Operand dst, Operand base, IdentifierTableIndex property)
         : Instruction(Type::DeleteById)
@@ -1345,7 +1345,7 @@ private:
     IdentifierTableIndex m_property;
 };
 
-class DeleteByIdWithThis final : public Instruction {
+class JS_API DeleteByIdWithThis final : public Instruction {
 public:
     DeleteByIdWithThis(Operand dst, Operand base, Operand this_value, IdentifierTableIndex property)
         : Instruction(Type::DeleteByIdWithThis)
@@ -1377,7 +1377,7 @@ private:
     IdentifierTableIndex m_property;
 };
 
-class GetByValue final : public Instruction {
+class JS_API GetByValue final : public Instruction {
 public:
     GetByValue(Operand dst, Operand base, Operand property, Optional<IdentifierTableIndex> base_identifier = {})
         : Instruction(Type::GetByValue)
@@ -1408,7 +1408,7 @@ private:
     Optional<IdentifierTableIndex> m_base_identifier;
 };
 
-class GetByValueWithThis final : public Instruction {
+class JS_API GetByValueWithThis final : public Instruction {
 public:
     GetByValueWithThis(Operand dst, Operand base, Operand property, Operand this_value)
         : Instruction(Type::GetByValueWithThis)
@@ -1441,7 +1441,7 @@ private:
     Operand m_this_value;
 };
 
-class PutByValue final : public Instruction {
+class JS_API PutByValue final : public Instruction {
 public:
     PutByValue(Operand base, Operand property, Operand src, PropertyKind kind = PropertyKind::KeyValue, Optional<IdentifierTableIndex> base_identifier = {})
         : Instruction(Type::PutByValue)
@@ -1475,7 +1475,7 @@ private:
     Optional<IdentifierTableIndex> m_base_identifier;
 };
 
-class PutByValueWithThis final : public Instruction {
+class JS_API PutByValueWithThis final : public Instruction {
 public:
     PutByValueWithThis(Operand base, Operand property, Operand this_value, Operand src, PropertyKind kind = PropertyKind::KeyValue)
         : Instruction(Type::PutByValueWithThis)
@@ -1511,7 +1511,7 @@ private:
     PropertyKind m_kind;
 };
 
-class DeleteByValue final : public Instruction {
+class JS_API DeleteByValue final : public Instruction {
 public:
     DeleteByValue(Operand dst, Operand base, Operand property)
         : Instruction(Type::DeleteByValue)
@@ -1540,7 +1540,7 @@ private:
     Operand m_property;
 };
 
-class DeleteByValueWithThis final : public Instruction {
+class JS_API DeleteByValueWithThis final : public Instruction {
 public:
     DeleteByValueWithThis(Operand dst, Operand base, Operand this_value, Operand property)
         : Instruction(Type::DeleteByValueWithThis)
@@ -1573,7 +1573,7 @@ private:
     Operand m_property;
 };
 
-class Jump final : public Instruction {
+class JS_API Jump final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1595,7 +1595,7 @@ protected:
     Label m_target;
 };
 
-class JumpIf final : public Instruction {
+class JS_API JumpIf final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1628,7 +1628,7 @@ private:
     Label m_false_target;
 };
 
-class JumpTrue final : public Instruction {
+class JS_API JumpTrue final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1657,7 +1657,7 @@ private:
     Label m_target;
 };
 
-class JumpFalse final : public Instruction {
+class JS_API JumpFalse final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1697,7 +1697,7 @@ private:
     X(StrictlyInequals, strict_inequals, !=)
 
 #define DECLARE_COMPARISON_OP(op_TitleCase, op_snake_case, numeric_operator)                         \
-    class Jump##op_TitleCase final : public Instruction {                                            \
+    class JS_API Jump##op_TitleCase final : public Instruction {                                     \
     public:                                                                                          \
         constexpr static bool IsTerminator = true;                                                   \
                                                                                                      \
@@ -1737,7 +1737,7 @@ private:
 
 JS_ENUMERATE_COMPARISON_OPS(DECLARE_COMPARISON_OP)
 
-class JumpNullish final : public Instruction {
+class JS_API JumpNullish final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1770,7 +1770,7 @@ private:
     Label m_false_target;
 };
 
-class JumpUndefined final : public Instruction {
+class JS_API JumpUndefined final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -1809,7 +1809,7 @@ enum class CallType : u8 {
     DirectEval,
 };
 
-class Call final : public Instruction {
+class JS_API Call final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -1858,7 +1858,7 @@ private:
     Operand m_arguments[];
 };
 
-class CallBuiltin final : public Instruction {
+class JS_API CallBuiltin final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -1911,7 +1911,7 @@ private:
     Operand m_arguments[];
 };
 
-class CallConstruct final : public Instruction {
+class JS_API CallConstruct final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -1956,7 +1956,7 @@ private:
     Operand m_arguments[];
 };
 
-class CallDirectEval final : public Instruction {
+class JS_API CallDirectEval final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -2005,7 +2005,7 @@ private:
     Operand m_arguments[];
 };
 
-class CallWithArgumentArray final : public Instruction {
+class JS_API CallWithArgumentArray final : public Instruction {
 public:
     CallWithArgumentArray(CallType type, Operand dst, Operand callee, Operand this_value, Operand arguments, Optional<StringTableIndex> expression_string = {})
         : Instruction(Type::CallWithArgumentArray)
@@ -2044,7 +2044,7 @@ private:
     Optional<StringTableIndex> m_expression_string;
 };
 
-class SuperCallWithArgumentArray : public Instruction {
+class JS_API SuperCallWithArgumentArray : public Instruction {
 public:
     explicit SuperCallWithArgumentArray(Operand dst, Operand arguments, bool is_synthetic)
         : Instruction(Type::SuperCallWithArgumentArray)
@@ -2072,7 +2072,7 @@ private:
     bool m_is_synthetic;
 };
 
-class NewClass final : public Instruction {
+class JS_API NewClass final : public Instruction {
 public:
     static constexpr bool IsVariableLength = true;
 
@@ -2123,7 +2123,7 @@ private:
     Optional<Operand> m_element_keys[];
 };
 
-class NewFunction final : public Instruction {
+class JS_API NewFunction final : public Instruction {
 public:
     explicit NewFunction(Operand dst, FunctionNode const& function_node, Optional<IdentifierTableIndex> lhs_name, Optional<Operand> home_object = {})
         : Instruction(Type::NewFunction)
@@ -2155,7 +2155,7 @@ private:
     Optional<Operand> m_home_object;
 };
 
-class BlockDeclarationInstantiation final : public Instruction {
+class JS_API BlockDeclarationInstantiation final : public Instruction {
 public:
     explicit BlockDeclarationInstantiation(ScopeNode const& scope_node)
         : Instruction(Type::BlockDeclarationInstantiation)
@@ -2172,7 +2172,7 @@ private:
     ScopeNode const& m_scope_node;
 };
 
-class Return final : public Instruction {
+class JS_API Return final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2195,7 +2195,7 @@ private:
     Operand m_value;
 };
 
-class Increment final : public Instruction {
+class JS_API Increment final : public Instruction {
 public:
     explicit Increment(Operand dst)
         : Instruction(Type::Increment)
@@ -2216,7 +2216,7 @@ private:
     Operand m_dst;
 };
 
-class PostfixIncrement final : public Instruction {
+class JS_API PostfixIncrement final : public Instruction {
 public:
     explicit PostfixIncrement(Operand dst, Operand src)
         : Instruction(Type::PostfixIncrement)
@@ -2241,7 +2241,7 @@ private:
     Operand m_src;
 };
 
-class Decrement final : public Instruction {
+class JS_API Decrement final : public Instruction {
 public:
     explicit Decrement(Operand dst)
         : Instruction(Type::Decrement)
@@ -2262,7 +2262,7 @@ private:
     Operand m_dst;
 };
 
-class PostfixDecrement final : public Instruction {
+class JS_API PostfixDecrement final : public Instruction {
 public:
     explicit PostfixDecrement(Operand dst, Operand src)
         : Instruction(Type::PostfixDecrement)
@@ -2287,7 +2287,7 @@ private:
     Operand m_src;
 };
 
-class Throw final : public Instruction {
+class JS_API Throw final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2310,7 +2310,7 @@ private:
     Operand m_src;
 };
 
-class ThrowIfNotObject final : public Instruction {
+class JS_API ThrowIfNotObject final : public Instruction {
 public:
     ThrowIfNotObject(Operand src)
         : Instruction(Type::ThrowIfNotObject)
@@ -2331,7 +2331,7 @@ private:
     Operand m_src;
 };
 
-class ThrowIfNullish final : public Instruction {
+class JS_API ThrowIfNullish final : public Instruction {
 public:
     explicit ThrowIfNullish(Operand src)
         : Instruction(Type::ThrowIfNullish)
@@ -2352,7 +2352,7 @@ private:
     Operand m_src;
 };
 
-class ThrowIfTDZ final : public Instruction {
+class JS_API ThrowIfTDZ final : public Instruction {
 public:
     explicit ThrowIfTDZ(Operand src)
         : Instruction(Type::ThrowIfTDZ)
@@ -2373,7 +2373,7 @@ private:
     Operand m_src;
 };
 
-class EnterUnwindContext final : public Instruction {
+class JS_API EnterUnwindContext final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2395,7 +2395,7 @@ private:
     Label m_entry_point;
 };
 
-class ScheduleJump final : public Instruction {
+class JS_API ScheduleJump final : public Instruction {
 public:
     // Note: We use this instruction to tell the next `finally` block to
     //       continue execution with a specific break/continue target;
@@ -2419,7 +2419,7 @@ private:
     Label m_target;
 };
 
-class LeaveLexicalEnvironment final : public Instruction {
+class JS_API LeaveLexicalEnvironment final : public Instruction {
 public:
     LeaveLexicalEnvironment()
         : Instruction(Type::LeaveLexicalEnvironment)
@@ -2430,7 +2430,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class LeavePrivateEnvironment final : public Instruction {
+class JS_API LeavePrivateEnvironment final : public Instruction {
 public:
     LeavePrivateEnvironment()
         : Instruction(Type::LeavePrivateEnvironment)
@@ -2441,7 +2441,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class LeaveUnwindContext final : public Instruction {
+class JS_API LeaveUnwindContext final : public Instruction {
 public:
     LeaveUnwindContext()
         : Instruction(Type::LeaveUnwindContext)
@@ -2452,7 +2452,7 @@ public:
     ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
-class ContinuePendingUnwind final : public Instruction {
+class JS_API ContinuePendingUnwind final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2474,7 +2474,7 @@ private:
     Label m_resume_target;
 };
 
-class Yield final : public Instruction {
+class JS_API Yield final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2511,7 +2511,7 @@ private:
     Operand m_value;
 };
 
-class PrepareYield final : public Instruction {
+class JS_API PrepareYield final : public Instruction {
 public:
     explicit PrepareYield(Operand dest, Operand value)
         : Instruction(Type::PrepareYield)
@@ -2536,7 +2536,7 @@ private:
     Operand m_value;
 };
 
-class Await final : public Instruction {
+class JS_API Await final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2566,7 +2566,7 @@ private:
     Operand m_argument;
 };
 
-class GetIterator final : public Instruction {
+class JS_API GetIterator final : public Instruction {
 public:
     GetIterator(Operand dst, Operand iterable, IteratorHint hint = IteratorHint::Sync)
         : Instruction(Type::GetIterator)
@@ -2594,7 +2594,7 @@ private:
     IteratorHint m_hint { IteratorHint::Sync };
 };
 
-class GetObjectFromIteratorRecord final : public Instruction {
+class JS_API GetObjectFromIteratorRecord final : public Instruction {
 public:
     GetObjectFromIteratorRecord(Operand object, Operand iterator_record)
         : Instruction(Type::GetObjectFromIteratorRecord)
@@ -2619,7 +2619,7 @@ private:
     Operand m_iterator_record;
 };
 
-class GetNextMethodFromIteratorRecord final : public Instruction {
+class JS_API GetNextMethodFromIteratorRecord final : public Instruction {
 public:
     GetNextMethodFromIteratorRecord(Operand next_method, Operand iterator_record)
         : Instruction(Type::GetNextMethodFromIteratorRecord)
@@ -2644,7 +2644,7 @@ private:
     Operand m_iterator_record;
 };
 
-class GetMethod final : public Instruction {
+class JS_API GetMethod final : public Instruction {
 public:
     GetMethod(Operand dst, Operand object, IdentifierTableIndex property)
         : Instruction(Type::GetMethod)
@@ -2672,7 +2672,7 @@ private:
     IdentifierTableIndex m_property;
 };
 
-class GetObjectPropertyIterator final : public Instruction {
+class JS_API GetObjectPropertyIterator final : public Instruction {
 public:
     GetObjectPropertyIterator(Operand dst, Operand object)
         : Instruction(Type::GetObjectPropertyIterator)
@@ -2697,7 +2697,7 @@ private:
     Operand m_object;
 };
 
-class IteratorClose final : public Instruction {
+class JS_API IteratorClose final : public Instruction {
 public:
     IteratorClose(Operand iterator_record, Completion::Type completion_type, Optional<Value> completion_value)
         : Instruction(Type::IteratorClose)
@@ -2724,7 +2724,7 @@ private:
     Optional<Value> m_completion_value;
 };
 
-class AsyncIteratorClose final : public Instruction {
+class JS_API AsyncIteratorClose final : public Instruction {
 public:
     AsyncIteratorClose(Operand iterator_record, Completion::Type completion_type, Optional<Value> completion_value)
         : Instruction(Type::AsyncIteratorClose)
@@ -2751,7 +2751,7 @@ private:
     Optional<Value> m_completion_value;
 };
 
-class IteratorNext final : public Instruction {
+class JS_API IteratorNext final : public Instruction {
 public:
     IteratorNext(Operand dst, Operand iterator_record)
         : Instruction(Type::IteratorNext)
@@ -2776,7 +2776,7 @@ private:
     Operand m_iterator_record;
 };
 
-class IteratorNextUnpack final : public Instruction {
+class JS_API IteratorNextUnpack final : public Instruction {
 public:
     IteratorNextUnpack(Operand dst_value, Operand dst_done, Operand iterator_record)
         : Instruction(Type::IteratorNextUnpack)
@@ -2805,7 +2805,7 @@ private:
     Operand m_iterator_record;
 };
 
-class ResolveThisBinding final : public Instruction {
+class JS_API ResolveThisBinding final : public Instruction {
 public:
     ResolveThisBinding()
         : Instruction(Type::ResolveThisBinding)
@@ -2817,7 +2817,7 @@ public:
     void visit_operands_impl(Function<void(Operand&)>) { }
 };
 
-class ResolveSuperBase final : public Instruction {
+class JS_API ResolveSuperBase final : public Instruction {
 public:
     explicit ResolveSuperBase(Operand dst)
         : Instruction(Type::ResolveSuperBase)
@@ -2838,7 +2838,7 @@ private:
     Operand m_dst;
 };
 
-class GetNewTarget final : public Instruction {
+class JS_API GetNewTarget final : public Instruction {
 public:
     explicit GetNewTarget(Operand dst)
         : Instruction(Type::GetNewTarget)
@@ -2859,7 +2859,7 @@ private:
     Operand m_dst;
 };
 
-class GetImportMeta final : public Instruction {
+class JS_API GetImportMeta final : public Instruction {
 public:
     explicit GetImportMeta(Operand dst)
         : Instruction(Type::GetImportMeta)
@@ -2880,7 +2880,7 @@ private:
     Operand m_dst;
 };
 
-class TypeofBinding final : public Instruction {
+class JS_API TypeofBinding final : public Instruction {
 public:
     TypeofBinding(Operand dst, IdentifierTableIndex identifier)
         : Instruction(Type::TypeofBinding)
@@ -2905,7 +2905,7 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class End final : public Instruction {
+class JS_API End final : public Instruction {
 public:
     constexpr static bool IsTerminator = true;
 
@@ -2927,7 +2927,7 @@ private:
     Operand m_value;
 };
 
-class Dump final : public Instruction {
+class JS_API Dump final : public Instruction {
 public:
     explicit Dump(StringView text, Operand value)
         : Instruction(Type::Dump)
diff --git a/Libraries/LibJS/Bytecode/Operand.h b/Libraries/LibJS/Bytecode/Operand.h
index ccda535bafe..34653328580 100644
--- a/Libraries/LibJS/Bytecode/Operand.h
+++ b/Libraries/LibJS/Bytecode/Operand.h
@@ -11,7 +11,7 @@
 
 namespace JS::Bytecode {
 
-class Operand {
+class JS_API Operand {
 public:
     enum class Type
 #if ARCH(AARCH64)
diff --git a/Libraries/LibJS/Bytecode/RegexTable.h b/Libraries/LibJS/Bytecode/RegexTable.h
index f5d7dd302bb..b16d918416e 100644
--- a/Libraries/LibJS/Bytecode/RegexTable.h
+++ b/Libraries/LibJS/Bytecode/RegexTable.h
@@ -9,6 +9,7 @@
 #include <AK/DistinctNumeric.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
+#include <LibJS/Forward.h>
 #include <LibRegex/RegexParser.h>
 
 namespace JS::Bytecode {
@@ -21,7 +22,7 @@ struct ParsedRegex {
     regex::RegexOptions<ECMAScriptFlags> flags;
 };
 
-class RegexTable {
+class JS_API RegexTable {
     AK_MAKE_NONMOVABLE(RegexTable);
     AK_MAKE_NONCOPYABLE(RegexTable);
 
diff --git a/Libraries/LibJS/Bytecode/Register.h b/Libraries/LibJS/Bytecode/Register.h
index 41d8973a814..b151018e3c0 100644
--- a/Libraries/LibJS/Bytecode/Register.h
+++ b/Libraries/LibJS/Bytecode/Register.h
@@ -7,10 +7,11 @@
 #pragma once
 
 #include <AK/Format.h>
+#include <LibJS/Forward.h>
 
 namespace JS::Bytecode {
 
-class Register {
+class JS_API Register {
 public:
     constexpr static u32 accumulator_index = 0;
 
diff --git a/Libraries/LibJS/Bytecode/ScopedOperand.h b/Libraries/LibJS/Bytecode/ScopedOperand.h
index 01aa33aa59e..1f1d7da9557 100644
--- a/Libraries/LibJS/Bytecode/ScopedOperand.h
+++ b/Libraries/LibJS/Bytecode/ScopedOperand.h
@@ -11,7 +11,7 @@
 
 namespace JS::Bytecode {
 
-class ScopedOperandImpl : public RefCounted<ScopedOperandImpl> {
+class JS_API ScopedOperandImpl : public RefCounted<ScopedOperandImpl> {
 public:
     ScopedOperandImpl(Generator& generator, Operand operand)
         : m_generator(generator)
@@ -29,7 +29,7 @@ private:
     Operand m_operand;
 };
 
-class ScopedOperand {
+class JS_API ScopedOperand {
 public:
     explicit ScopedOperand(Generator& generator, Operand operand)
         : m_impl(adopt_ref(*new ScopedOperandImpl(generator, operand)))
diff --git a/Libraries/LibJS/Bytecode/StringTable.h b/Libraries/LibJS/Bytecode/StringTable.h
index 48a2ac31fdd..ced297754fc 100644
--- a/Libraries/LibJS/Bytecode/StringTable.h
+++ b/Libraries/LibJS/Bytecode/StringTable.h
@@ -9,6 +9,7 @@
 #include <AK/DistinctNumeric.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
+#include <LibJS/Forward.h>
 
 namespace JS::Bytecode {
 
@@ -18,7 +19,7 @@ struct StringTableIndex {
     u32 value { 0 };
 };
 
-class StringTable {
+class JS_API StringTable {
     AK_MAKE_NONMOVABLE(StringTable);
     AK_MAKE_NONCOPYABLE(StringTable);
 
diff --git a/Libraries/LibJS/CMakeLists.txt b/Libraries/LibJS/CMakeLists.txt
index b64a0305029..e5a8abc81a7 100644
--- a/Libraries/LibJS/CMakeLists.txt
+++ b/Libraries/LibJS/CMakeLists.txt
@@ -267,7 +267,7 @@ set(SOURCES
     Token.cpp
 )
 
-serenity_lib(LibJS js)
+serenity_lib(LibJS js EXPLICIT_SYMBOL_EXPORT)
 target_link_libraries(LibJS PRIVATE LibCore LibCrypto LibFileSystem LibRegex LibSyntax LibGC)
 
 # Link LibUnicode publicly to ensure ICU data (which is in libicudata.a) is available in any process using LibJS.
diff --git a/Libraries/LibJS/Console.h b/Libraries/LibJS/Console.h
index 3f799e55a44..d2cff02ec8c 100644
--- a/Libraries/LibJS/Console.h
+++ b/Libraries/LibJS/Console.h
@@ -23,7 +23,7 @@ namespace JS {
 class ConsoleClient;
 
 // https://console.spec.whatwg.org
-class Console : public Cell {
+class JS_API Console : public Cell {
     GC_CELL(Console, Cell);
     GC_DECLARE_ALLOCATOR(Console);
 
@@ -105,7 +105,7 @@ private:
     Vector<Group> m_group_stack;
 };
 
-class ConsoleClient : public Cell {
+class JS_API ConsoleClient : public Cell {
     GC_CELL(ConsoleClient, Cell);
     GC_DECLARE_ALLOCATOR(ConsoleClient);
 
diff --git a/Libraries/LibJS/Contrib/Test262/262Object.h b/Libraries/LibJS/Contrib/Test262/262Object.h
index c8a8d133b78..34e0519e1bf 100644
--- a/Libraries/LibJS/Contrib/Test262/262Object.h
+++ b/Libraries/LibJS/Contrib/Test262/262Object.h
@@ -13,7 +13,7 @@
 
 namespace JS::Test262 {
 
-class $262Object final : public Object {
+class JS_API $262Object final : public Object {
     JS_OBJECT($262Object, Object);
     GC_DECLARE_ALLOCATOR($262Object);
 
diff --git a/Libraries/LibJS/Contrib/Test262/AgentObject.h b/Libraries/LibJS/Contrib/Test262/AgentObject.h
index 1f86cc3d41e..4c32795c44b 100644
--- a/Libraries/LibJS/Contrib/Test262/AgentObject.h
+++ b/Libraries/LibJS/Contrib/Test262/AgentObject.h
@@ -11,7 +11,7 @@
 
 namespace JS::Test262 {
 
-class AgentObject final : public Object {
+class JS_API AgentObject final : public Object {
     JS_OBJECT(AgentObject, Object);
     GC_DECLARE_ALLOCATOR(AgentObject);
 
diff --git a/Libraries/LibJS/Contrib/Test262/IsHTMLDDA.h b/Libraries/LibJS/Contrib/Test262/IsHTMLDDA.h
index 15a68756716..f39145fb6df 100644
--- a/Libraries/LibJS/Contrib/Test262/IsHTMLDDA.h
+++ b/Libraries/LibJS/Contrib/Test262/IsHTMLDDA.h
@@ -10,7 +10,7 @@
 
 namespace JS::Test262 {
 
-class IsHTMLDDA final : public NativeFunction {
+class JS_API IsHTMLDDA final : public NativeFunction {
     JS_OBJECT(IsHTMLDDA, NativeFunction);
     GC_DECLARE_ALLOCATOR(IsHTMLDDA);
 
diff --git a/Libraries/LibJS/CyclicModule.h b/Libraries/LibJS/CyclicModule.h
index 2bdd1e84a74..bef8b5c2237 100644
--- a/Libraries/LibJS/CyclicModule.h
+++ b/Libraries/LibJS/CyclicModule.h
@@ -23,7 +23,7 @@ enum class ModuleStatus {
 };
 
 // 16.2.1.5 Cyclic Module Records, https://tc39.es/ecma262/#cyclic-module-record
-class CyclicModule : public Module {
+class JS_API CyclicModule : public Module {
     GC_CELL(CyclicModule, Module);
     GC_DECLARE_ALLOCATOR(CyclicModule);
 
@@ -76,8 +76,8 @@ protected:
     Optional<u32> m_pending_async_dependencies;           // [[PendingAsyncDependencies]]
 };
 
-void inner_module_loading(VM&, GraphLoadingState& state, GC::Ref<Module>);
-void continue_module_loading(GraphLoadingState&, ThrowCompletionOr<GC::Ref<Module>> const&);
-void continue_dynamic_import(GC::Ref<PromiseCapability>, ThrowCompletionOr<GC::Ref<Module>> const& module_completion);
+JS_API void inner_module_loading(VM&, GraphLoadingState& state, GC::Ref<Module>);
+JS_API void continue_module_loading(GraphLoadingState&, ThrowCompletionOr<GC::Ref<Module>> const&);
+JS_API void continue_dynamic_import(GC::Ref<PromiseCapability>, ThrowCompletionOr<GC::Ref<Module>> const& module_completion);
 
 }
diff --git a/Libraries/LibJS/Forward.h b/Libraries/LibJS/Forward.h
index 32ff57af473..9a06b2bc512 100644
--- a/Libraries/LibJS/Forward.h
+++ b/Libraries/LibJS/Forward.h
@@ -9,6 +9,7 @@
 
 #include <AK/Concepts.h>
 #include <AK/Types.h>
+#include <LibJS/Export.h>
 
 #define JS_DECLARE_NATIVE_FUNCTION(name) \
     static JS::ThrowCompletionOr<JS::Value> name(JS::VM&)
diff --git a/Libraries/LibJS/Heap/Cell.h b/Libraries/LibJS/Heap/Cell.h
index 7c04a550abd..4893867f8e5 100644
--- a/Libraries/LibJS/Heap/Cell.h
+++ b/Libraries/LibJS/Heap/Cell.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class Cell : public GC::Cell {
+class JS_API Cell : public GC::Cell {
     GC_CELL(Cell, GC::Cell);
 
 public:
diff --git a/Libraries/LibJS/Lexer.h b/Libraries/LibJS/Lexer.h
index 052e7910bc3..6b6a2646be5 100644
--- a/Libraries/LibJS/Lexer.h
+++ b/Libraries/LibJS/Lexer.h
@@ -12,10 +12,11 @@
 #include <AK/HashMap.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
+#include <LibJS/Export.h>
 
 namespace JS {
 
-class Lexer {
+class JS_API Lexer {
 public:
     explicit Lexer(StringView source, StringView filename = "(unknown)"sv, size_t line_number = 1, size_t line_column = 0);
 
diff --git a/Libraries/LibJS/MarkupGenerator.h b/Libraries/LibJS/MarkupGenerator.h
index 72eccb6dd7d..58be1a37c6f 100644
--- a/Libraries/LibJS/MarkupGenerator.h
+++ b/Libraries/LibJS/MarkupGenerator.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class MarkupGenerator {
+class JS_API MarkupGenerator {
 public:
     static ErrorOr<String> html_from_source(StringView);
     static ErrorOr<String> html_from_value(Value);
diff --git a/Libraries/LibJS/Module.h b/Libraries/LibJS/Module.h
index c94c26df135..7e1a1f5ace0 100644
--- a/Libraries/LibJS/Module.h
+++ b/Libraries/LibJS/Module.h
@@ -57,7 +57,7 @@ struct ResolvedBinding {
 };
 
 // https://tc39.es/ecma262/#graphloadingstate-record
-struct GraphLoadingState : public Cell {
+struct JS_API GraphLoadingState : public Cell {
     GC_CELL(GraphLoadingState, Cell);
     GC_DECLARE_ALLOCATOR(GraphLoadingState);
 
@@ -88,7 +88,7 @@ private:
 };
 
 // 16.2.1.4 Abstract Module Records, https://tc39.es/ecma262/#sec-abstract-module-records
-class Module : public Cell {
+class JS_API Module : public Cell {
     GC_CELL(Module, Cell);
     GC_DECLARE_ALLOCATOR(Module);
 
@@ -150,6 +150,6 @@ private:
 class CyclicModule;
 struct GraphLoadingState;
 
-void finish_loading_imported_module(ImportedModuleReferrer, ModuleRequest const&, ImportedModulePayload, ThrowCompletionOr<GC::Ref<Module>> const&);
+JS_API void finish_loading_imported_module(ImportedModuleReferrer, ModuleRequest const&, ImportedModulePayload, ThrowCompletionOr<GC::Ref<Module>> const&);
 
 }
diff --git a/Libraries/LibJS/Parser.cpp b/Libraries/LibJS/Parser.cpp
index ffcbf450682..80cde29b8e4 100644
--- a/Libraries/LibJS/Parser.cpp
+++ b/Libraries/LibJS/Parser.cpp
@@ -5204,8 +5204,8 @@ Parser::ForbiddenTokens Parser::ForbiddenTokens::forbid(std::initializer_list<To
     return result;
 }
 
-template NonnullRefPtr<FunctionExpression> Parser::parse_function_node(u16, Optional<Position> const&);
-template NonnullRefPtr<FunctionDeclaration> Parser::parse_function_node(u16, Optional<Position> const&);
+template JS_API NonnullRefPtr<FunctionExpression> Parser::parse_function_node(u16, Optional<Position> const&);
+template JS_API NonnullRefPtr<FunctionDeclaration> Parser::parse_function_node(u16, Optional<Position> const&);
 
 NonnullRefPtr<Identifier const> Parser::create_identifier_and_register_in_current_scope(SourceRange range, FlyString string, Optional<DeclarationKind> declaration_kind)
 {
diff --git a/Libraries/LibJS/Parser.h b/Libraries/LibJS/Parser.h
index f2fee77a11a..ccd5165aa89 100644
--- a/Libraries/LibJS/Parser.h
+++ b/Libraries/LibJS/Parser.h
@@ -45,7 +45,7 @@ struct FunctionNodeParseOptions {
 
 class ScopePusher;
 
-class Parser {
+class JS_API Parser {
 public:
     struct EvalInitialState {
         bool in_eval_function_context { false };
diff --git a/Libraries/LibJS/ParserError.h b/Libraries/LibJS/ParserError.h
index eb48518aa60..d392b03d266 100644
--- a/Libraries/LibJS/ParserError.h
+++ b/Libraries/LibJS/ParserError.h
@@ -15,7 +15,7 @@
 
 namespace JS {
 
-struct ParserError {
+struct JS_API ParserError {
     String message;
     Optional<Position> position;
 
diff --git a/Libraries/LibJS/Print.h b/Libraries/LibJS/Print.h
index 995a5f798de..63f51d354ac 100644
--- a/Libraries/LibJS/Print.h
+++ b/Libraries/LibJS/Print.h
@@ -20,6 +20,6 @@ struct PrintContext {
     bool disable_string_quotes { false };
 };
 
-ErrorOr<void> print(JS::Value value, PrintContext&);
+JS_API ErrorOr<void> print(JS::Value value, PrintContext&);
 
 }
diff --git a/Libraries/LibJS/Runtime/AbstractOperations.h b/Libraries/LibJS/Runtime/AbstractOperations.h
index f9450e60d0f..cafbca7a250 100644
--- a/Libraries/LibJS/Runtime/AbstractOperations.h
+++ b/Libraries/LibJS/Runtime/AbstractOperations.h
@@ -23,27 +23,27 @@
 
 namespace JS {
 
-GC::Ref<DeclarativeEnvironment> new_declarative_environment(Environment&);
-GC::Ref<ObjectEnvironment> new_object_environment(Object&, bool is_with_environment, Environment*);
-GC::Ref<FunctionEnvironment> new_function_environment(ECMAScriptFunctionObject&, Object* new_target);
-GC::Ref<PrivateEnvironment> new_private_environment(VM& vm, PrivateEnvironment* outer);
-GC::Ref<Environment> get_this_environment(VM&);
-bool can_be_held_weakly(Value);
-Object* get_super_constructor(VM&);
-ThrowCompletionOr<Value> require_object_coercible(VM&, Value);
-ThrowCompletionOr<Value> call_impl(VM&, Value function, Value this_value, ReadonlySpan<Value> arguments = {});
-ThrowCompletionOr<Value> call_impl(VM&, FunctionObject& function, Value this_value, ReadonlySpan<Value> arguments = {});
-ThrowCompletionOr<GC::Ref<Object>> construct_impl(VM&, FunctionObject&, ReadonlySpan<Value> arguments = {}, FunctionObject* new_target = nullptr);
-ThrowCompletionOr<size_t> length_of_array_like(VM&, Object const&);
-ThrowCompletionOr<GC::RootVector<Value>> create_list_from_array_like(VM&, Value, Function<ThrowCompletionOr<void>(Value)> = {});
-ThrowCompletionOr<FunctionObject*> species_constructor(VM&, Object const&, FunctionObject& default_constructor);
-ThrowCompletionOr<Realm*> get_function_realm(VM&, FunctionObject const&);
-ThrowCompletionOr<void> initialize_bound_name(VM&, FlyString const&, Value, Environment*);
-bool is_compatible_property_descriptor(bool extensible, PropertyDescriptor const&, Optional<PropertyDescriptor> const& current);
-bool validate_and_apply_property_descriptor(Object*, PropertyKey const&, bool extensible, PropertyDescriptor const&, Optional<PropertyDescriptor> const& current);
-ThrowCompletionOr<Object*> get_prototype_from_constructor(VM&, FunctionObject const& constructor, GC::Ref<Object> (Intrinsics::*intrinsic_default_prototype)());
-Object* create_unmapped_arguments_object(VM&, ReadonlySpan<Value> arguments);
-Object* create_mapped_arguments_object(VM&, FunctionObject&, NonnullRefPtr<FunctionParameters const> const&, ReadonlySpan<Value> arguments, Environment&);
+JS_API GC::Ref<DeclarativeEnvironment> new_declarative_environment(Environment&);
+JS_API GC::Ref<ObjectEnvironment> new_object_environment(Object&, bool is_with_environment, Environment*);
+JS_API GC::Ref<FunctionEnvironment> new_function_environment(ECMAScriptFunctionObject&, Object* new_target);
+JS_API GC::Ref<PrivateEnvironment> new_private_environment(VM& vm, PrivateEnvironment* outer);
+JS_API GC::Ref<Environment> get_this_environment(VM&);
+JS_API bool can_be_held_weakly(Value);
+JS_API Object* get_super_constructor(VM&);
+JS_API ThrowCompletionOr<Value> require_object_coercible(VM&, Value);
+JS_API ThrowCompletionOr<Value> call_impl(VM&, Value function, Value this_value, ReadonlySpan<Value> arguments = {});
+JS_API ThrowCompletionOr<Value> call_impl(VM&, FunctionObject& function, Value this_value, ReadonlySpan<Value> arguments = {});
+JS_API ThrowCompletionOr<GC::Ref<Object>> construct_impl(VM&, FunctionObject&, ReadonlySpan<Value> arguments = {}, FunctionObject* new_target = nullptr);
+JS_API ThrowCompletionOr<size_t> length_of_array_like(VM&, Object const&);
+JS_API ThrowCompletionOr<GC::RootVector<Value>> create_list_from_array_like(VM&, Value, Function<ThrowCompletionOr<void>(Value)> = {});
+JS_API ThrowCompletionOr<FunctionObject*> species_constructor(VM&, Object const&, FunctionObject& default_constructor);
+JS_API ThrowCompletionOr<Realm*> get_function_realm(VM&, FunctionObject const&);
+JS_API ThrowCompletionOr<void> initialize_bound_name(VM&, FlyString const&, Value, Environment*);
+JS_API bool is_compatible_property_descriptor(bool extensible, PropertyDescriptor const&, Optional<PropertyDescriptor> const& current);
+JS_API bool validate_and_apply_property_descriptor(Object*, PropertyKey const&, bool extensible, PropertyDescriptor const&, Optional<PropertyDescriptor> const& current);
+JS_API ThrowCompletionOr<Object*> get_prototype_from_constructor(VM&, FunctionObject const& constructor, GC::Ref<Object> (Intrinsics::*intrinsic_default_prototype)());
+JS_API Object* create_unmapped_arguments_object(VM&, ReadonlySpan<Value> arguments);
+JS_API Object* create_mapped_arguments_object(VM&, FunctionObject&, NonnullRefPtr<FunctionParameters const> const&, ReadonlySpan<Value> arguments, Environment&);
 
 // 2.1.1 DisposeCapability Records, https://tc39.es/proposal-explicit-resource-management/#sec-disposecapability-records
 struct DisposeCapability {
@@ -61,30 +61,30 @@ struct DisposableResource {
     GC::Ptr<FunctionObject> dispose_method;  // [[DisposeMethod]]
 };
 
-DisposeCapability new_dispose_capability();
-ThrowCompletionOr<void> add_disposable_resource(VM&, DisposeCapability&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> = {});
-ThrowCompletionOr<DisposableResource> create_disposable_resource(VM&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> = {});
-ThrowCompletionOr<GC::Ptr<FunctionObject>> get_dispose_method(VM&, Value, Environment::InitializeBindingHint);
-Completion dispose(VM&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> method);
-Completion dispose_resources(VM&, DisposeCapability&, Completion);
+JS_API DisposeCapability new_dispose_capability();
+JS_API ThrowCompletionOr<void> add_disposable_resource(VM&, DisposeCapability&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> = {});
+JS_API ThrowCompletionOr<DisposableResource> create_disposable_resource(VM&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> = {});
+JS_API ThrowCompletionOr<GC::Ptr<FunctionObject>> get_dispose_method(VM&, Value, Environment::InitializeBindingHint);
+JS_API Completion dispose(VM&, Value, Environment::InitializeBindingHint, GC::Ptr<FunctionObject> method);
+JS_API Completion dispose_resources(VM&, DisposeCapability&, Completion);
 
-ThrowCompletionOr<Value> perform_import_call(VM&, Value specifier, Value options_value);
+JS_API ThrowCompletionOr<Value> perform_import_call(VM&, Value specifier, Value options_value);
 
 enum class CanonicalIndexMode {
     DetectNumericRoundtrip,
     IgnoreNumericRoundtrip,
 };
-[[nodiscard]] CanonicalIndex canonical_numeric_index_string(PropertyKey const&, CanonicalIndexMode needs_numeric);
-ThrowCompletionOr<String> get_substitution(VM&, Utf16View const& matched, Utf16View const& str, size_t position, Span<Value> captures, Value named_captures, Value replacement);
+[[nodiscard]] JS_API CanonicalIndex canonical_numeric_index_string(PropertyKey const&, CanonicalIndexMode needs_numeric);
+JS_API ThrowCompletionOr<String> get_substitution(VM&, Utf16View const& matched, Utf16View const& str, size_t position, Span<Value> captures, Value named_captures, Value replacement);
 
 enum class CallerMode {
     Strict,
     NonStrict
 };
 
-ThrowCompletionOr<Value> perform_eval(VM&, Value, CallerMode, EvalMode);
+JS_API ThrowCompletionOr<Value> perform_eval(VM&, Value, CallerMode, EvalMode);
 
-ThrowCompletionOr<void> eval_declaration_instantiation(VM& vm, Program const& program, Environment* variable_environment, Environment* lexical_environment, PrivateEnvironment* private_environment, bool strict);
+JS_API ThrowCompletionOr<void> eval_declaration_instantiation(VM& vm, Program const& program, Environment* variable_environment, Environment* lexical_environment, PrivateEnvironment* private_environment, bool strict);
 
 // 7.3.14 Call ( F, V [ , argumentsList ] ), https://tc39.es/ecma262/#sec-call
 ALWAYS_INLINE ThrowCompletionOr<Value> call(VM& vm, Value function, Value this_value, ReadonlySpan<Value> arguments_list)
@@ -342,8 +342,8 @@ enum class OptionType {
 struct Required { };
 using OptionDefault = Variant<Required, Empty, bool, StringView, double>;
 
-ThrowCompletionOr<GC::Ref<Object>> get_options_object(VM&, Value options);
-ThrowCompletionOr<Value> get_option(VM&, Object const& options, PropertyKey const& property, OptionType type, ReadonlySpan<StringView> values, OptionDefault const&);
+JS_API ThrowCompletionOr<GC::Ref<Object>> get_options_object(VM&, Value options);
+JS_API ThrowCompletionOr<Value> get_option(VM&, Object const& options, PropertyKey const& property, OptionType type, ReadonlySpan<StringView> values, OptionDefault const&);
 
 template<size_t Size>
 ThrowCompletionOr<Value> get_option(VM& vm, Object const& options, PropertyKey const& property, OptionType type, StringView const (&values)[Size], OptionDefault const& default_)
@@ -364,9 +364,9 @@ enum class RoundingMode {
     HalfEven,
 };
 
-ThrowCompletionOr<RoundingMode> get_rounding_mode_option(VM&, Object const& options, RoundingMode fallback);
-ThrowCompletionOr<u64> get_rounding_increment_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<RoundingMode> get_rounding_mode_option(VM&, Object const& options, RoundingMode fallback);
+JS_API ThrowCompletionOr<u64> get_rounding_increment_option(VM&, Object const& options);
 
-Crypto::SignedBigInteger big_floor(Crypto::SignedBigInteger const& numerator, Crypto::UnsignedBigInteger const& denominator);
+JS_API Crypto::SignedBigInteger big_floor(Crypto::SignedBigInteger const& numerator, Crypto::UnsignedBigInteger const& denominator);
 
 }
diff --git a/Libraries/LibJS/Runtime/Accessor.h b/Libraries/LibJS/Runtime/Accessor.h
index a9a25f4cce1..cc851e77f08 100644
--- a/Libraries/LibJS/Runtime/Accessor.h
+++ b/Libraries/LibJS/Runtime/Accessor.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class Accessor final : public Cell {
+class JS_API Accessor final : public Cell {
     GC_CELL(Accessor, Cell);
     GC_DECLARE_ALLOCATOR(Accessor);
 
diff --git a/Libraries/LibJS/Runtime/Agent.h b/Libraries/LibJS/Runtime/Agent.h
index 87f05eb94ed..25ce9cbdf9c 100644
--- a/Libraries/LibJS/Runtime/Agent.h
+++ b/Libraries/LibJS/Runtime/Agent.h
@@ -14,7 +14,7 @@
 namespace JS {
 
 // https://tc39.es/ecma262/#sec-agents
-class Agent {
+class JS_API Agent {
 public:
     enum class CanBlock {
         Yes,
@@ -38,6 +38,6 @@ private:
     CanBlock m_can_block { false };
 };
 
-bool agent_can_suspend(VM const&);
+JS_API bool agent_can_suspend(VM const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/AggregateError.h b/Libraries/LibJS/Runtime/AggregateError.h
index abf59437bb3..097830926f6 100644
--- a/Libraries/LibJS/Runtime/AggregateError.h
+++ b/Libraries/LibJS/Runtime/AggregateError.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class AggregateError : public Error {
+class JS_API AggregateError : public Error {
     JS_OBJECT(AggregateError, Error);
     GC_DECLARE_ALLOCATOR(AggregateError);
 
diff --git a/Libraries/LibJS/Runtime/AggregateErrorConstructor.h b/Libraries/LibJS/Runtime/AggregateErrorConstructor.h
index 3e09bf393a6..3a8c408234f 100644
--- a/Libraries/LibJS/Runtime/AggregateErrorConstructor.h
+++ b/Libraries/LibJS/Runtime/AggregateErrorConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AggregateErrorConstructor final : public NativeFunction {
+class JS_API AggregateErrorConstructor final : public NativeFunction {
     JS_OBJECT(AggregateErrorConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(AggregateErrorConstructor);
 
diff --git a/Libraries/LibJS/Runtime/AggregateErrorPrototype.h b/Libraries/LibJS/Runtime/AggregateErrorPrototype.h
index 18134c7139f..0749650bd92 100644
--- a/Libraries/LibJS/Runtime/AggregateErrorPrototype.h
+++ b/Libraries/LibJS/Runtime/AggregateErrorPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AggregateErrorPrototype final : public Object {
+class JS_API AggregateErrorPrototype final : public Object {
     JS_OBJECT(AggregateErrorPrototype, Object);
     GC_DECLARE_ALLOCATOR(AggregateErrorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ArgumentsObject.h b/Libraries/LibJS/Runtime/ArgumentsObject.h
index b6cafebec41..b6f7d3bab26 100644
--- a/Libraries/LibJS/Runtime/ArgumentsObject.h
+++ b/Libraries/LibJS/Runtime/ArgumentsObject.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class ArgumentsObject final : public Object {
+class JS_API ArgumentsObject final : public Object {
     JS_OBJECT(ArgumentsObject, Object);
     GC_DECLARE_ALLOCATOR(ArgumentsObject);
 
diff --git a/Libraries/LibJS/Runtime/Array.h b/Libraries/LibJS/Runtime/Array.h
index c0997ba090c..b541046c60f 100644
--- a/Libraries/LibJS/Runtime/Array.h
+++ b/Libraries/LibJS/Runtime/Array.h
@@ -19,7 +19,7 @@
 
 namespace JS {
 
-class Array : public Object {
+class JS_API Array : public Object {
     JS_OBJECT(Array, Object);
     GC_DECLARE_ALLOCATOR(Array);
 
@@ -81,7 +81,7 @@ enum class Holes {
     ReadThroughHoles,
 };
 
-ThrowCompletionOr<GC::RootVector<Value>> sort_indexed_properties(VM&, Object const&, size_t length, Function<ThrowCompletionOr<double>(Value, Value)> const& sort_compare, Holes holes);
-ThrowCompletionOr<double> compare_array_elements(VM&, Value x, Value y, FunctionObject* comparefn);
+JS_API ThrowCompletionOr<GC::RootVector<Value>> sort_indexed_properties(VM&, Object const&, size_t length, Function<ThrowCompletionOr<double>(Value, Value)> const& sort_compare, Holes holes);
+JS_API ThrowCompletionOr<double> compare_array_elements(VM&, Value x, Value y, FunctionObject* comparefn);
 
 }
diff --git a/Libraries/LibJS/Runtime/ArrayBuffer.h b/Libraries/LibJS/Runtime/ArrayBuffer.h
index 8ef9766cfd7..337cc429ebe 100644
--- a/Libraries/LibJS/Runtime/ArrayBuffer.h
+++ b/Libraries/LibJS/Runtime/ArrayBuffer.h
@@ -54,7 +54,7 @@ struct DataBlock {
     Shared is_shared = { Shared::No };
 };
 
-class ArrayBuffer : public Object {
+class JS_API ArrayBuffer : public Object {
     JS_OBJECT(ArrayBuffer, Object);
     GC_DECLARE_ALLOCATOR(ArrayBuffer);
 
@@ -145,14 +145,14 @@ private:
     Value m_detach_key;
 };
 
-ThrowCompletionOr<DataBlock> create_byte_data_block(VM& vm, size_t size);
-void copy_data_block_bytes(ByteBuffer& to_block, u64 to_index, ByteBuffer const& from_block, u64 from_index, u64 count);
-ThrowCompletionOr<ArrayBuffer*> allocate_array_buffer(VM&, FunctionObject& constructor, size_t byte_length, Optional<size_t> const& max_byte_length = {});
-ThrowCompletionOr<ArrayBuffer*> array_buffer_copy_and_detach(VM&, ArrayBuffer& array_buffer, Value new_length, PreserveResizability preserve_resizability);
-ThrowCompletionOr<void> detach_array_buffer(VM&, ArrayBuffer& array_buffer, Optional<Value> key = {});
-ThrowCompletionOr<Optional<size_t>> get_array_buffer_max_byte_length_option(VM&, Value options);
-ThrowCompletionOr<ArrayBuffer*> clone_array_buffer(VM&, ArrayBuffer& source_buffer, size_t source_byte_offset, size_t source_length);
-ThrowCompletionOr<GC::Ref<ArrayBuffer>> allocate_shared_array_buffer(VM&, FunctionObject& constructor, size_t byte_length);
+JS_API ThrowCompletionOr<DataBlock> create_byte_data_block(VM& vm, size_t size);
+JS_API void copy_data_block_bytes(ByteBuffer& to_block, u64 to_index, ByteBuffer const& from_block, u64 from_index, u64 count);
+JS_API ThrowCompletionOr<ArrayBuffer*> allocate_array_buffer(VM&, FunctionObject& constructor, size_t byte_length, Optional<size_t> const& max_byte_length = {});
+JS_API ThrowCompletionOr<ArrayBuffer*> array_buffer_copy_and_detach(VM&, ArrayBuffer& array_buffer, Value new_length, PreserveResizability preserve_resizability);
+JS_API ThrowCompletionOr<void> detach_array_buffer(VM&, ArrayBuffer& array_buffer, Optional<Value> key = {});
+JS_API ThrowCompletionOr<Optional<size_t>> get_array_buffer_max_byte_length_option(VM&, Value options);
+JS_API ThrowCompletionOr<ArrayBuffer*> clone_array_buffer(VM&, ArrayBuffer& source_buffer, size_t source_byte_offset, size_t source_length);
+JS_API ThrowCompletionOr<GC::Ref<ArrayBuffer>> allocate_shared_array_buffer(VM&, FunctionObject& constructor, size_t byte_length);
 
 // 25.1.3.2 ArrayBufferByteLength ( arrayBuffer, order ), https://tc39.es/ecma262/#sec-arraybufferbytelength
 inline size_t array_buffer_byte_length(ArrayBuffer const& array_buffer, ArrayBuffer::Order)
diff --git a/Libraries/LibJS/Runtime/ArrayBufferConstructor.h b/Libraries/LibJS/Runtime/ArrayBufferConstructor.h
index c0ef3480341..28edea1a656 100644
--- a/Libraries/LibJS/Runtime/ArrayBufferConstructor.h
+++ b/Libraries/LibJS/Runtime/ArrayBufferConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ArrayBufferConstructor final : public NativeFunction {
+class JS_API ArrayBufferConstructor final : public NativeFunction {
     JS_OBJECT(ArrayBufferConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ArrayBufferConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ArrayBufferPrototype.h b/Libraries/LibJS/Runtime/ArrayBufferPrototype.h
index 73f4c52f920..95ffa228aa8 100644
--- a/Libraries/LibJS/Runtime/ArrayBufferPrototype.h
+++ b/Libraries/LibJS/Runtime/ArrayBufferPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ArrayBufferPrototype final : public PrototypeObject<ArrayBufferPrototype, ArrayBuffer> {
+class JS_API ArrayBufferPrototype final : public PrototypeObject<ArrayBufferPrototype, ArrayBuffer> {
     JS_PROTOTYPE_OBJECT(ArrayBufferPrototype, ArrayBuffer, ArrayBuffer);
     GC_DECLARE_ALLOCATOR(ArrayBufferPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ArrayConstructor.h b/Libraries/LibJS/Runtime/ArrayConstructor.h
index 6d31b080606..e1abc4c0818 100644
--- a/Libraries/LibJS/Runtime/ArrayConstructor.h
+++ b/Libraries/LibJS/Runtime/ArrayConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ArrayConstructor final : public NativeFunction {
+class JS_API ArrayConstructor final : public NativeFunction {
     JS_OBJECT(ArrayConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ArrayConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ArrayIterator.h b/Libraries/LibJS/Runtime/ArrayIterator.h
index 93f3cc5375f..12e814f42a7 100644
--- a/Libraries/LibJS/Runtime/ArrayIterator.h
+++ b/Libraries/LibJS/Runtime/ArrayIterator.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ArrayIterator final : public Object
+class JS_API ArrayIterator final : public Object
     , public BuiltinIterator {
     JS_OBJECT(ArrayIterator, Object);
     GC_DECLARE_ALLOCATOR(ArrayIterator);
diff --git a/Libraries/LibJS/Runtime/ArrayIteratorPrototype.h b/Libraries/LibJS/Runtime/ArrayIteratorPrototype.h
index febf50fd5bf..e73e58ceae6 100644
--- a/Libraries/LibJS/Runtime/ArrayIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/ArrayIteratorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ArrayIteratorPrototype final : public PrototypeObject<ArrayIteratorPrototype, ArrayIterator> {
+class JS_API ArrayIteratorPrototype final : public PrototypeObject<ArrayIteratorPrototype, ArrayIterator> {
     JS_PROTOTYPE_OBJECT(ArrayIteratorPrototype, ArrayIterator, ArrayIterator);
     GC_DECLARE_ALLOCATOR(ArrayIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ArrayPrototype.h b/Libraries/LibJS/Runtime/ArrayPrototype.h
index b0091574b3b..0a06e4697cf 100644
--- a/Libraries/LibJS/Runtime/ArrayPrototype.h
+++ b/Libraries/LibJS/Runtime/ArrayPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ArrayPrototype final : public Array {
+class JS_API ArrayPrototype final : public Array {
     JS_OBJECT(ArrayPrototype, Array);
     GC_DECLARE_ALLOCATOR(ArrayPrototype);
 
@@ -64,6 +64,6 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(with);
 };
 
-ThrowCompletionOr<void> array_merge_sort(VM&, Function<ThrowCompletionOr<double>(Value, Value)> const& compare_func, GC::RootVector<Value>& arr_to_sort);
+JS_API ThrowCompletionOr<void> array_merge_sort(VM&, Function<ThrowCompletionOr<double>(Value, Value)> const& compare_func, GC::RootVector<Value>& arr_to_sort);
 
 }
diff --git a/Libraries/LibJS/Runtime/AsyncDisposableStack.h b/Libraries/LibJS/Runtime/AsyncDisposableStack.h
index faa4cba73af..f40b0097208 100644
--- a/Libraries/LibJS/Runtime/AsyncDisposableStack.h
+++ b/Libraries/LibJS/Runtime/AsyncDisposableStack.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class AsyncDisposableStack final : public Object {
+class JS_API AsyncDisposableStack final : public Object {
     JS_OBJECT(AsyncDisposableStack, Object);
     GC_DECLARE_ALLOCATOR(AsyncDisposableStack);
 
diff --git a/Libraries/LibJS/Runtime/AsyncDisposableStackConstructor.h b/Libraries/LibJS/Runtime/AsyncDisposableStackConstructor.h
index 59854563ee9..e8897953a70 100644
--- a/Libraries/LibJS/Runtime/AsyncDisposableStackConstructor.h
+++ b/Libraries/LibJS/Runtime/AsyncDisposableStackConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncDisposableStackConstructor final : public NativeFunction {
+class JS_API AsyncDisposableStackConstructor final : public NativeFunction {
     JS_OBJECT(AsyncDisposableStackConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(AsyncDisposableStackConstructor);
 
diff --git a/Libraries/LibJS/Runtime/AsyncDisposableStackPrototype.h b/Libraries/LibJS/Runtime/AsyncDisposableStackPrototype.h
index 712bba568c6..39caf5d0019 100644
--- a/Libraries/LibJS/Runtime/AsyncDisposableStackPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncDisposableStackPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class AsyncDisposableStackPrototype final : public PrototypeObject<AsyncDisposableStackPrototype, AsyncDisposableStack> {
+class JS_API AsyncDisposableStackPrototype final : public PrototypeObject<AsyncDisposableStackPrototype, AsyncDisposableStack> {
     JS_PROTOTYPE_OBJECT(AsyncDisposableStackPrototype, AsyncDisposableStack, AsyncDisposableStack);
     GC_DECLARE_ALLOCATOR(AsyncDisposableStackPrototype);
 
diff --git a/Libraries/LibJS/Runtime/AsyncFromSyncIterator.h b/Libraries/LibJS/Runtime/AsyncFromSyncIterator.h
index cf8a314ecac..29dbd6e7db0 100644
--- a/Libraries/LibJS/Runtime/AsyncFromSyncIterator.h
+++ b/Libraries/LibJS/Runtime/AsyncFromSyncIterator.h
@@ -13,7 +13,7 @@
 namespace JS {
 
 // 27.1.4.3 Properties of Async-from-Sync Iterator Instances, https://tc39.es/ecma262/#sec-properties-of-async-from-sync-iterator-instances
-class AsyncFromSyncIterator final : public Object {
+class JS_API AsyncFromSyncIterator final : public Object {
     JS_OBJECT(AsyncFromSyncIterator, Object);
     GC_DECLARE_ALLOCATOR(AsyncFromSyncIterator);
 
diff --git a/Libraries/LibJS/Runtime/AsyncFromSyncIteratorPrototype.h b/Libraries/LibJS/Runtime/AsyncFromSyncIteratorPrototype.h
index 4995143e681..1dd078539dd 100644
--- a/Libraries/LibJS/Runtime/AsyncFromSyncIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncFromSyncIteratorPrototype.h
@@ -15,7 +15,7 @@
 namespace JS {
 
 // 27.1.4.2 The %AsyncFromSyncIteratorPrototype% Object, https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%-object
-class AsyncFromSyncIteratorPrototype final : public PrototypeObject<AsyncFromSyncIteratorPrototype, AsyncFromSyncIterator> {
+class JS_API AsyncFromSyncIteratorPrototype final : public PrototypeObject<AsyncFromSyncIteratorPrototype, AsyncFromSyncIterator> {
     JS_PROTOTYPE_OBJECT(AsyncFromSyncIteratorPrototype, AsyncFromSyncIterator, AsyncFromSyncIterator);
     GC_DECLARE_ALLOCATOR(AsyncFromSyncIteratorPrototype);
 
@@ -31,6 +31,6 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(throw_);
 };
 
-GC::Ref<IteratorRecord> create_async_from_sync_iterator(VM&, GC::Ref<IteratorRecord> sync_iterator);
+JS_API GC::Ref<IteratorRecord> create_async_from_sync_iterator(VM&, GC::Ref<IteratorRecord> sync_iterator);
 
 }
diff --git a/Libraries/LibJS/Runtime/AsyncFunctionConstructor.h b/Libraries/LibJS/Runtime/AsyncFunctionConstructor.h
index 01ff33e4517..8802bc2cde1 100644
--- a/Libraries/LibJS/Runtime/AsyncFunctionConstructor.h
+++ b/Libraries/LibJS/Runtime/AsyncFunctionConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncFunctionConstructor final : public NativeFunction {
+class JS_API AsyncFunctionConstructor final : public NativeFunction {
     JS_OBJECT(AsyncFunctionConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(AsyncFunctionConstructor);
 
diff --git a/Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.h b/Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.h
index 54b0d67d8cd..5519a860cd5 100644
--- a/Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.h
+++ b/Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.h
@@ -14,7 +14,7 @@
 
 namespace JS {
 
-class AsyncFunctionDriverWrapper final : public Promise {
+class JS_API AsyncFunctionDriverWrapper final : public Promise {
     JS_OBJECT(AsyncFunctionDriverWrapper, Promise);
     GC_DECLARE_ALLOCATOR(AsyncFunctionDriverWrapper);
 
diff --git a/Libraries/LibJS/Runtime/AsyncFunctionPrototype.h b/Libraries/LibJS/Runtime/AsyncFunctionPrototype.h
index 6bf3351f573..db45d3cd574 100644
--- a/Libraries/LibJS/Runtime/AsyncFunctionPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncFunctionPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncFunctionPrototype final : public Object {
+class JS_API AsyncFunctionPrototype final : public Object {
     JS_OBJECT(AsyncFunctionPrototype, Object);
     GC_DECLARE_ALLOCATOR(AsyncFunctionPrototype);
 
diff --git a/Libraries/LibJS/Runtime/AsyncGenerator.h b/Libraries/LibJS/Runtime/AsyncGenerator.h
index 3be3e206e4d..84f122ab0c1 100644
--- a/Libraries/LibJS/Runtime/AsyncGenerator.h
+++ b/Libraries/LibJS/Runtime/AsyncGenerator.h
@@ -15,7 +15,7 @@
 namespace JS {
 
 // 27.6.2 Properties of AsyncGenerator Instances, https://tc39.es/ecma262/#sec-properties-of-asyncgenerator-intances
-class AsyncGenerator final : public Object {
+class JS_API AsyncGenerator final : public Object {
     JS_OBJECT(AsyncGenerator, Object);
     GC_DECLARE_ALLOCATOR(AsyncGenerator);
 
diff --git a/Libraries/LibJS/Runtime/AsyncGeneratorFunctionConstructor.h b/Libraries/LibJS/Runtime/AsyncGeneratorFunctionConstructor.h
index 9365ea495a2..ecfb6daf015 100644
--- a/Libraries/LibJS/Runtime/AsyncGeneratorFunctionConstructor.h
+++ b/Libraries/LibJS/Runtime/AsyncGeneratorFunctionConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncGeneratorFunctionConstructor final : public NativeFunction {
+class JS_API AsyncGeneratorFunctionConstructor final : public NativeFunction {
     JS_OBJECT(AsyncGeneratorFunctionConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(AsyncGeneratorFunctionConstructor);
 
diff --git a/Libraries/LibJS/Runtime/AsyncGeneratorFunctionPrototype.h b/Libraries/LibJS/Runtime/AsyncGeneratorFunctionPrototype.h
index 2790d5abccc..986aa9b07ba 100644
--- a/Libraries/LibJS/Runtime/AsyncGeneratorFunctionPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncGeneratorFunctionPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncGeneratorFunctionPrototype final : public PrototypeObject<AsyncGeneratorFunctionPrototype, AsyncGeneratorFunction> {
+class JS_API AsyncGeneratorFunctionPrototype final : public PrototypeObject<AsyncGeneratorFunctionPrototype, AsyncGeneratorFunction> {
     JS_PROTOTYPE_OBJECT(AsyncGeneratorFunctionPrototype, AsyncGeneratorFunction, AsyncGeneratorFunction);
     GC_DECLARE_ALLOCATOR(AsyncGeneratorFunctionPrototype);
 
diff --git a/Libraries/LibJS/Runtime/AsyncGeneratorPrototype.h b/Libraries/LibJS/Runtime/AsyncGeneratorPrototype.h
index daea67ba0a5..1099d823924 100644
--- a/Libraries/LibJS/Runtime/AsyncGeneratorPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncGeneratorPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class AsyncGeneratorPrototype final : public PrototypeObject<AsyncGeneratorPrototype, AsyncGenerator> {
+class JS_API AsyncGeneratorPrototype final : public PrototypeObject<AsyncGeneratorPrototype, AsyncGenerator> {
     JS_PROTOTYPE_OBJECT(AsyncGeneratorPrototype, AsyncGenerator, AsyncGenerator)
     GC_DECLARE_ALLOCATOR(AsyncGeneratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/AsyncIteratorPrototype.h b/Libraries/LibJS/Runtime/AsyncIteratorPrototype.h
index f1eb3895617..66e2878b6b4 100644
--- a/Libraries/LibJS/Runtime/AsyncIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/AsyncIteratorPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AsyncIteratorPrototype final : public Object {
+class JS_API AsyncIteratorPrototype final : public Object {
     JS_OBJECT(AsyncIteratorPrototype, Object)
     GC_DECLARE_ALLOCATOR(AsyncIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/AtomicsObject.h b/Libraries/LibJS/Runtime/AtomicsObject.h
index 3ace57e2a55..8b26c370078 100644
--- a/Libraries/LibJS/Runtime/AtomicsObject.h
+++ b/Libraries/LibJS/Runtime/AtomicsObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class AtomicsObject : public Object {
+class JS_API AtomicsObject : public Object {
     JS_OBJECT(AtomicsObject, Object);
     GC_DECLARE_ALLOCATOR(AtomicsObject);
 
diff --git a/Libraries/LibJS/Runtime/BigInt.h b/Libraries/LibJS/Runtime/BigInt.h
index a4e3b09b638..fb5af7aa011 100644
--- a/Libraries/LibJS/Runtime/BigInt.h
+++ b/Libraries/LibJS/Runtime/BigInt.h
@@ -15,7 +15,7 @@
 
 namespace JS {
 
-class BigInt final : public Cell {
+class JS_API BigInt final : public Cell {
     GC_CELL(BigInt, Cell);
     GC_DECLARE_ALLOCATOR(BigInt);
 
@@ -35,6 +35,6 @@ private:
     Crypto::SignedBigInteger m_big_integer;
 };
 
-ThrowCompletionOr<GC::Ref<BigInt>> number_to_bigint(VM&, Value);
+JS_API ThrowCompletionOr<GC::Ref<BigInt>> number_to_bigint(VM&, Value);
 
 }
diff --git a/Libraries/LibJS/Runtime/BigIntConstructor.h b/Libraries/LibJS/Runtime/BigIntConstructor.h
index e2218b8f68c..efb421ed61a 100644
--- a/Libraries/LibJS/Runtime/BigIntConstructor.h
+++ b/Libraries/LibJS/Runtime/BigIntConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class BigIntConstructor final : public NativeFunction {
+class JS_API BigIntConstructor final : public NativeFunction {
     JS_OBJECT(BigIntConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(BigIntConstructor);
 
diff --git a/Libraries/LibJS/Runtime/BigIntObject.h b/Libraries/LibJS/Runtime/BigIntObject.h
index 49f5d6021a8..eab16ae643f 100644
--- a/Libraries/LibJS/Runtime/BigIntObject.h
+++ b/Libraries/LibJS/Runtime/BigIntObject.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class BigIntObject final : public Object {
+class JS_API BigIntObject final : public Object {
     JS_OBJECT(BigIntObject, Object);
     GC_DECLARE_ALLOCATOR(BigIntObject);
 
diff --git a/Libraries/LibJS/Runtime/BigIntPrototype.h b/Libraries/LibJS/Runtime/BigIntPrototype.h
index ba88a43b33e..3c06a0dc745 100644
--- a/Libraries/LibJS/Runtime/BigIntPrototype.h
+++ b/Libraries/LibJS/Runtime/BigIntPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class BigIntPrototype final : public Object {
+class JS_API BigIntPrototype final : public Object {
     JS_OBJECT(BigIntPrototype, Object);
     GC_DECLARE_ALLOCATOR(BigIntPrototype);
 
diff --git a/Libraries/LibJS/Runtime/BooleanConstructor.h b/Libraries/LibJS/Runtime/BooleanConstructor.h
index 1fcedc295bc..225eba68882 100644
--- a/Libraries/LibJS/Runtime/BooleanConstructor.h
+++ b/Libraries/LibJS/Runtime/BooleanConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class BooleanConstructor final : public NativeFunction {
+class JS_API BooleanConstructor final : public NativeFunction {
     JS_OBJECT(BooleanConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(BooleanConstructor);
 
diff --git a/Libraries/LibJS/Runtime/BooleanObject.h b/Libraries/LibJS/Runtime/BooleanObject.h
index 21fb5f5e146..5ea1b60eadc 100644
--- a/Libraries/LibJS/Runtime/BooleanObject.h
+++ b/Libraries/LibJS/Runtime/BooleanObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class BooleanObject : public Object {
+class JS_API BooleanObject : public Object {
     JS_OBJECT(BooleanObject, Object);
     GC_DECLARE_ALLOCATOR(BooleanObject);
 
diff --git a/Libraries/LibJS/Runtime/BooleanPrototype.h b/Libraries/LibJS/Runtime/BooleanPrototype.h
index 10651a55474..b81bfe7c172 100644
--- a/Libraries/LibJS/Runtime/BooleanPrototype.h
+++ b/Libraries/LibJS/Runtime/BooleanPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class BooleanPrototype final : public BooleanObject {
+class JS_API BooleanPrototype final : public BooleanObject {
     JS_OBJECT(BooleanPrototype, BooleanObject);
     GC_DECLARE_ALLOCATOR(BooleanPrototype);
 
diff --git a/Libraries/LibJS/Runtime/BoundFunction.h b/Libraries/LibJS/Runtime/BoundFunction.h
index bf3d7b9c012..61e405483e4 100644
--- a/Libraries/LibJS/Runtime/BoundFunction.h
+++ b/Libraries/LibJS/Runtime/BoundFunction.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class BoundFunction final : public FunctionObject {
+class JS_API BoundFunction final : public FunctionObject {
     JS_OBJECT(BoundFunction, FunctionObject);
     GC_DECLARE_ALLOCATOR(BoundFunction);
 
diff --git a/Libraries/LibJS/Runtime/Completion.cpp b/Libraries/LibJS/Runtime/Completion.cpp
index 117fed983d7..7402fdf1ed1 100644
--- a/Libraries/LibJS/Runtime/Completion.cpp
+++ b/Libraries/LibJS/Runtime/Completion.cpp
@@ -6,6 +6,7 @@
  */
 
 #include <AK/TypeCasts.h>
+#include <LibJS/Export.h>
 #include <LibJS/Runtime/Agent.h>
 #include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/NativeFunction.h>
@@ -17,7 +18,7 @@
 
 namespace JS {
 
-bool g_log_all_js_exceptions = false;
+JS_API bool g_log_all_js_exceptions = false;
 
 Completion::Completion(ThrowCompletionOr<Value> const& throw_completion_or_value)
 {
diff --git a/Libraries/LibJS/Runtime/Completion.h b/Libraries/LibJS/Runtime/Completion.h
index c1a45a06956..bb6060e504e 100644
--- a/Libraries/LibJS/Runtime/Completion.h
+++ b/Libraries/LibJS/Runtime/Completion.h
@@ -49,7 +49,7 @@ namespace JS {
     })
 
 // 6.2.3 The Completion Record Specification Type, https://tc39.es/ecma262/#sec-completion-record-specification-type
-class [[nodiscard]] Completion {
+class [[nodiscard]] JS_API Completion {
 public:
     enum class Type {
         Empty,
@@ -335,7 +335,7 @@ private:
     Value m_value;
 };
 
-ThrowCompletionOr<Value> await(VM&, Value);
+JS_API ThrowCompletionOr<Value> await(VM&, Value);
 
 // 6.2.4.1 NormalCompletion ( value ), https://tc39.es/ecma262/#sec-normalcompletion
 inline Completion normal_completion(Value value)
@@ -345,6 +345,6 @@ inline Completion normal_completion(Value value)
 }
 
 // 6.2.4.2 ThrowCompletion ( value ), https://tc39.es/ecma262/#sec-throwcompletion
-Completion throw_completion(Value);
+JS_API Completion throw_completion(Value);
 
 }
diff --git a/Libraries/LibJS/Runtime/CompletionCell.h b/Libraries/LibJS/Runtime/CompletionCell.h
index da1b286a151..4e339786fda 100644
--- a/Libraries/LibJS/Runtime/CompletionCell.h
+++ b/Libraries/LibJS/Runtime/CompletionCell.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class CompletionCell final : public Cell {
+class JS_API CompletionCell final : public Cell {
     GC_CELL(CompletionCell, Cell);
     GC_DECLARE_ALLOCATOR(CompletionCell);
 
diff --git a/Libraries/LibJS/Runtime/ConsoleObject.h b/Libraries/LibJS/Runtime/ConsoleObject.h
index b7586908ac8..b3f5f3f4189 100644
--- a/Libraries/LibJS/Runtime/ConsoleObject.h
+++ b/Libraries/LibJS/Runtime/ConsoleObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ConsoleObject final : public Object {
+class JS_API ConsoleObject final : public Object {
     JS_OBJECT(ConsoleObject, Object);
     GC_DECLARE_ALLOCATOR(ConsoleObject);
 
diff --git a/Libraries/LibJS/Runtime/ConsoleObjectPrototype.h b/Libraries/LibJS/Runtime/ConsoleObjectPrototype.h
index 705e7adb55e..039fb6e0842 100644
--- a/Libraries/LibJS/Runtime/ConsoleObjectPrototype.h
+++ b/Libraries/LibJS/Runtime/ConsoleObjectPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ConsoleObjectPrototype final : public Object {
+class JS_API ConsoleObjectPrototype final : public Object {
     JS_OBJECT(ConsoleObjectPrototype, Object);
     GC_DECLARE_ALLOCATOR(ConsoleObjectPrototype);
 
diff --git a/Libraries/LibJS/Runtime/DataView.h b/Libraries/LibJS/Runtime/DataView.h
index e451c022bf2..04e91f69acb 100644
--- a/Libraries/LibJS/Runtime/DataView.h
+++ b/Libraries/LibJS/Runtime/DataView.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class DataView : public Object {
+class JS_API DataView : public Object {
     JS_OBJECT(DataView, Object);
     GC_DECLARE_ALLOCATOR(DataView);
 
@@ -42,8 +42,8 @@ struct DataViewWithBufferWitness {
     ByteLength cached_buffer_byte_length; // [[CachedBufferByteLength]]
 };
 
-DataViewWithBufferWitness make_data_view_with_buffer_witness_record(DataView const&, ArrayBuffer::Order);
-u32 get_view_byte_length(DataViewWithBufferWitness const&);
-bool is_view_out_of_bounds(DataViewWithBufferWitness const&);
+JS_API DataViewWithBufferWitness make_data_view_with_buffer_witness_record(DataView const&, ArrayBuffer::Order);
+JS_API u32 get_view_byte_length(DataViewWithBufferWitness const&);
+JS_API bool is_view_out_of_bounds(DataViewWithBufferWitness const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/DataViewConstructor.h b/Libraries/LibJS/Runtime/DataViewConstructor.h
index 476b79c297f..3a314656c4d 100644
--- a/Libraries/LibJS/Runtime/DataViewConstructor.h
+++ b/Libraries/LibJS/Runtime/DataViewConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class DataViewConstructor final : public NativeFunction {
+class JS_API DataViewConstructor final : public NativeFunction {
     JS_OBJECT(DataViewConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DataViewConstructor);
 
diff --git a/Libraries/LibJS/Runtime/DataViewPrototype.h b/Libraries/LibJS/Runtime/DataViewPrototype.h
index 9689e4a049c..d29b40aa9db 100644
--- a/Libraries/LibJS/Runtime/DataViewPrototype.h
+++ b/Libraries/LibJS/Runtime/DataViewPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class DataViewPrototype final : public PrototypeObject<DataViewPrototype, DataView> {
+class JS_API DataViewPrototype final : public PrototypeObject<DataViewPrototype, DataView> {
     JS_PROTOTYPE_OBJECT(DataViewPrototype, DataView, DataView);
     GC_DECLARE_ALLOCATOR(DataViewPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Date.h b/Libraries/LibJS/Runtime/Date.h
index f96ae10e658..897572fcf5c 100644
--- a/Libraries/LibJS/Runtime/Date.h
+++ b/Libraries/LibJS/Runtime/Date.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class Date final : public Object {
+class JS_API Date final : public Object {
     JS_OBJECT(Date, Object);
     GC_DECLARE_ALLOCATOR(Date);
 
@@ -63,36 +63,36 @@ constexpr inline double ms_per_day = 86'400'000;
 constexpr inline double ns_per_day = 86'400'000'000'000;
 extern Crypto::SignedBigInteger const ns_per_day_bigint;
 
-double day(double);
-double time_within_day(double);
-u16 days_in_year(i32);
-double day_from_year(i32);
-double time_from_year(i32);
-i32 year_from_time(double);
-u16 day_within_year(double);
-bool in_leap_year(double);
-u8 month_from_time(double);
-u8 date_from_time(double);
-u8 week_day(double);
-u8 hour_from_time(double);
-u8 min_from_time(double);
-u8 sec_from_time(double);
-u16 ms_from_time(double);
-Crypto::SignedBigInteger get_utc_epoch_nanoseconds(Temporal::ISODateTime const&);
-Vector<Crypto::SignedBigInteger> get_named_time_zone_epoch_nanoseconds(StringView time_zone_identifier, Temporal::ISODateTime const&);
-Unicode::TimeZoneOffset get_named_time_zone_offset_nanoseconds(StringView time_zone_identifier, Crypto::SignedBigInteger const& epoch_nanoseconds);
-Unicode::TimeZoneOffset get_named_time_zone_offset_milliseconds(StringView time_zone_identifier, double epoch_milliseconds);
-String system_time_zone_identifier();
-void clear_system_time_zone_cache();
-double local_time(double time);
-double utc_time(double time);
-double make_time(double hour, double min, double sec, double ms);
-double make_day(double year, double month, double date);
-double make_date(double day, double time);
-double time_clip(double time);
-bool is_offset_time_zone_identifier(StringView offset_string);
-ThrowCompletionOr<double> parse_date_time_utc_offset(VM&, StringView offset_string);
-double parse_date_time_utc_offset(StringView offset_string);
-double parse_date_time_utc_offset(Temporal::TimeZoneOffset const&);
+JS_API double day(double);
+JS_API double time_within_day(double);
+JS_API u16 days_in_year(i32);
+JS_API double day_from_year(i32);
+JS_API double time_from_year(i32);
+JS_API i32 year_from_time(double);
+JS_API u16 day_within_year(double);
+JS_API bool in_leap_year(double);
+JS_API u8 month_from_time(double);
+JS_API u8 date_from_time(double);
+JS_API u8 week_day(double);
+JS_API u8 hour_from_time(double);
+JS_API u8 min_from_time(double);
+JS_API u8 sec_from_time(double);
+JS_API u16 ms_from_time(double);
+JS_API Crypto::SignedBigInteger get_utc_epoch_nanoseconds(Temporal::ISODateTime const&);
+JS_API Vector<Crypto::SignedBigInteger> get_named_time_zone_epoch_nanoseconds(StringView time_zone_identifier, Temporal::ISODateTime const&);
+JS_API Unicode::TimeZoneOffset get_named_time_zone_offset_nanoseconds(StringView time_zone_identifier, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API Unicode::TimeZoneOffset get_named_time_zone_offset_milliseconds(StringView time_zone_identifier, double epoch_milliseconds);
+JS_API String system_time_zone_identifier();
+JS_API void clear_system_time_zone_cache();
+JS_API double local_time(double time);
+JS_API double utc_time(double time);
+JS_API double make_time(double hour, double min, double sec, double ms);
+JS_API double make_day(double year, double month, double date);
+JS_API double make_date(double day, double time);
+JS_API double time_clip(double time);
+JS_API bool is_offset_time_zone_identifier(StringView offset_string);
+JS_API ThrowCompletionOr<double> parse_date_time_utc_offset(VM&, StringView offset_string);
+JS_API double parse_date_time_utc_offset(StringView offset_string);
+JS_API double parse_date_time_utc_offset(Temporal::TimeZoneOffset const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/DateConstructor.h b/Libraries/LibJS/Runtime/DateConstructor.h
index c8a108d6884..d6ec1846a45 100644
--- a/Libraries/LibJS/Runtime/DateConstructor.h
+++ b/Libraries/LibJS/Runtime/DateConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class DateConstructor final : public NativeFunction {
+class JS_API DateConstructor final : public NativeFunction {
     JS_OBJECT(DateConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DateConstructor);
 
diff --git a/Libraries/LibJS/Runtime/DatePrototype.h b/Libraries/LibJS/Runtime/DatePrototype.h
index bb28e970806..47fc9cf9788 100644
--- a/Libraries/LibJS/Runtime/DatePrototype.h
+++ b/Libraries/LibJS/Runtime/DatePrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class DatePrototype final : public PrototypeObject<DatePrototype, Date> {
+class JS_API DatePrototype final : public PrototypeObject<DatePrototype, Date> {
     JS_PROTOTYPE_OBJECT(DatePrototype, Date, Date);
     GC_DECLARE_ALLOCATOR(DatePrototype);
 
@@ -74,10 +74,10 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(symbol_to_primitive);
 };
 
-ThrowCompletionOr<double> this_time_value(VM&, Value value);
-ByteString time_string(double time);
-ByteString date_string(double time);
-ByteString time_zone_string(double time);
-ByteString to_date_string(double time);
+JS_API ThrowCompletionOr<double> this_time_value(VM&, Value value);
+JS_API ByteString time_string(double time);
+JS_API ByteString date_string(double time);
+JS_API ByteString time_zone_string(double time);
+JS_API ByteString to_date_string(double time);
 
 }
diff --git a/Libraries/LibJS/Runtime/DeclarativeEnvironment.h b/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
index 639b78fb5e0..734d8164476 100644
--- a/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
+++ b/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
@@ -15,7 +15,7 @@
 
 namespace JS {
 
-class DeclarativeEnvironment : public Environment {
+class JS_API DeclarativeEnvironment : public Environment {
     JS_ENVIRONMENT(DeclarativeEnvironment, Environment);
     GC_DECLARE_ALLOCATOR(DeclarativeEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/DisposableStack.h b/Libraries/LibJS/Runtime/DisposableStack.h
index 89c9c064a64..e0d14084a98 100644
--- a/Libraries/LibJS/Runtime/DisposableStack.h
+++ b/Libraries/LibJS/Runtime/DisposableStack.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class DisposableStack final : public Object {
+class JS_API DisposableStack final : public Object {
     JS_OBJECT(DisposableStack, Object);
     GC_DECLARE_ALLOCATOR(DisposableStack);
 
diff --git a/Libraries/LibJS/Runtime/DisposableStackConstructor.h b/Libraries/LibJS/Runtime/DisposableStackConstructor.h
index 8b956e4e3d9..24c41455d62 100644
--- a/Libraries/LibJS/Runtime/DisposableStackConstructor.h
+++ b/Libraries/LibJS/Runtime/DisposableStackConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class DisposableStackConstructor final : public NativeFunction {
+class JS_API DisposableStackConstructor final : public NativeFunction {
     JS_OBJECT(DisposableStackConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DisposableStackConstructor);
 
diff --git a/Libraries/LibJS/Runtime/DisposableStackPrototype.h b/Libraries/LibJS/Runtime/DisposableStackPrototype.h
index 3995ab7d218..70a329caee6 100644
--- a/Libraries/LibJS/Runtime/DisposableStackPrototype.h
+++ b/Libraries/LibJS/Runtime/DisposableStackPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class DisposableStackPrototype final : public PrototypeObject<DisposableStackPrototype, DisposableStack> {
+class JS_API DisposableStackPrototype final : public PrototypeObject<DisposableStackPrototype, DisposableStack> {
     JS_PROTOTYPE_OBJECT(DisposableStackPrototype, DisposableStack, DisposableStack);
     GC_DECLARE_ALLOCATOR(DisposableStackPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h b/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
index ec1ce60ea8a..e89293a8c37 100644
--- a/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
+++ b/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
@@ -98,7 +98,7 @@ public:
 };
 
 // 10.2 ECMAScript Function Objects, https://tc39.es/ecma262/#sec-ecmascript-function-objects
-class ECMAScriptFunctionObject final : public FunctionObject {
+class JS_API ECMAScriptFunctionObject final : public FunctionObject {
     JS_OBJECT(ECMAScriptFunctionObject, FunctionObject);
     GC_DECLARE_ALLOCATOR(ECMAScriptFunctionObject);
 
diff --git a/Libraries/LibJS/Runtime/Environment.h b/Libraries/LibJS/Runtime/Environment.h
index 38607f3cc80..845e37b8329 100644
--- a/Libraries/LibJS/Runtime/Environment.h
+++ b/Libraries/LibJS/Runtime/Environment.h
@@ -19,7 +19,7 @@ struct Variable {
 
 #define JS_ENVIRONMENT(class_, base_class) GC_CELL(class_, base_class)
 
-class Environment : public Cell {
+class JS_API Environment : public Cell {
     GC_CELL(Environment, Cell);
 
 public:
diff --git a/Libraries/LibJS/Runtime/Error.h b/Libraries/LibJS/Runtime/Error.h
index f3ab985adff..dabac29548a 100644
--- a/Libraries/LibJS/Runtime/Error.h
+++ b/Libraries/LibJS/Runtime/Error.h
@@ -14,7 +14,7 @@
 
 namespace JS {
 
-struct TracebackFrame {
+struct JS_API TracebackFrame {
     FlyString function_name;
     [[nodiscard]] SourceRange const& source_range() const;
 
@@ -26,7 +26,7 @@ enum CompactTraceback {
     Yes,
 };
 
-class Error : public Object {
+class JS_API Error : public Object {
     JS_OBJECT(Error, Object);
     GC_DECLARE_ALLOCATOR(Error);
 
@@ -60,7 +60,7 @@ inline bool Object::fast_is<Error>() const { return is_error_object(); }
 //       our way of implementing the [[ErrorData]] internal slot, which is
 //       used in Object.prototype.toString().
 #define DECLARE_NATIVE_ERROR(ClassName, snake_name, PrototypeName, ConstructorName) \
-    class ClassName final : public Error {                                          \
+    class JS_API ClassName final : public Error {                                   \
         JS_OBJECT(ClassName, Error);                                                \
         GC_DECLARE_ALLOCATOR(ClassName);                                            \
                                                                                     \
diff --git a/Libraries/LibJS/Runtime/ErrorConstructor.h b/Libraries/LibJS/Runtime/ErrorConstructor.h
index 7582b217a37..0e888ff36e2 100644
--- a/Libraries/LibJS/Runtime/ErrorConstructor.h
+++ b/Libraries/LibJS/Runtime/ErrorConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ErrorConstructor final : public NativeFunction {
+class JS_API ErrorConstructor final : public NativeFunction {
     JS_OBJECT(ErrorConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ErrorConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ErrorPrototype.h b/Libraries/LibJS/Runtime/ErrorPrototype.h
index 1edcdc9e293..44467e179b0 100644
--- a/Libraries/LibJS/Runtime/ErrorPrototype.h
+++ b/Libraries/LibJS/Runtime/ErrorPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class ErrorPrototype final : public PrototypeObject<ErrorPrototype, Error> {
+class JS_API ErrorPrototype final : public PrototypeObject<ErrorPrototype, Error> {
     JS_PROTOTYPE_OBJECT(ErrorPrototype, Error, Error);
     GC_DECLARE_ALLOCATOR(ErrorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ExecutionContext.h b/Libraries/LibJS/Runtime/ExecutionContext.h
index 66b3a56230d..5916c6a2781 100644
--- a/Libraries/LibJS/Runtime/ExecutionContext.h
+++ b/Libraries/LibJS/Runtime/ExecutionContext.h
@@ -32,7 +32,7 @@ struct CachedSourceRange : public RefCounted<CachedSourceRange> {
 };
 
 // 9.4 Execution Contexts, https://tc39.es/ecma262/#sec-execution-contexts
-struct ExecutionContext {
+struct JS_API ExecutionContext {
     static NonnullOwnPtr<ExecutionContext> create(u32 registers_and_constants_and_locals_count, u32 arguments_count);
     [[nodiscard]] NonnullOwnPtr<ExecutionContext> copy() const;
 
diff --git a/Libraries/LibJS/Runtime/FinalizationRegistry.h b/Libraries/LibJS/Runtime/FinalizationRegistry.h
index ff090143298..a6baee61c80 100644
--- a/Libraries/LibJS/Runtime/FinalizationRegistry.h
+++ b/Libraries/LibJS/Runtime/FinalizationRegistry.h
@@ -17,7 +17,7 @@
 
 namespace JS {
 
-class FinalizationRegistry final
+class JS_API FinalizationRegistry final
     : public Object
     , public GC::WeakContainer {
     JS_OBJECT(FinalizationRegistry, Object);
diff --git a/Libraries/LibJS/Runtime/FinalizationRegistryConstructor.h b/Libraries/LibJS/Runtime/FinalizationRegistryConstructor.h
index ba26d81efd8..2e02c03e008 100644
--- a/Libraries/LibJS/Runtime/FinalizationRegistryConstructor.h
+++ b/Libraries/LibJS/Runtime/FinalizationRegistryConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class FinalizationRegistryConstructor final : public NativeFunction {
+class JS_API FinalizationRegistryConstructor final : public NativeFunction {
     JS_OBJECT(FinalizationRegistryConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(FinalizationRegistryConstructor);
 
diff --git a/Libraries/LibJS/Runtime/FinalizationRegistryPrototype.h b/Libraries/LibJS/Runtime/FinalizationRegistryPrototype.h
index ffe949be9c1..f365d52a684 100644
--- a/Libraries/LibJS/Runtime/FinalizationRegistryPrototype.h
+++ b/Libraries/LibJS/Runtime/FinalizationRegistryPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class FinalizationRegistryPrototype final : public PrototypeObject<FinalizationRegistryPrototype, FinalizationRegistry> {
+class JS_API FinalizationRegistryPrototype final : public PrototypeObject<FinalizationRegistryPrototype, FinalizationRegistry> {
     JS_PROTOTYPE_OBJECT(FinalizationRegistryPrototype, FinalizationRegistry, FinalizationRegistry);
     GC_DECLARE_ALLOCATOR(FinalizationRegistryPrototype);
 
diff --git a/Libraries/LibJS/Runtime/FunctionConstructor.h b/Libraries/LibJS/Runtime/FunctionConstructor.h
index 829be5976ee..f69ef24493b 100644
--- a/Libraries/LibJS/Runtime/FunctionConstructor.h
+++ b/Libraries/LibJS/Runtime/FunctionConstructor.h
@@ -16,9 +16,9 @@ struct ParameterArgumentsAndBody {
     String body;
 };
 
-ThrowCompletionOr<ParameterArgumentsAndBody> extract_parameter_arguments_and_body(VM&, Span<Value> arguments);
+JS_API ThrowCompletionOr<ParameterArgumentsAndBody> extract_parameter_arguments_and_body(VM&, Span<Value> arguments);
 
-class FunctionConstructor final : public NativeFunction {
+class JS_API FunctionConstructor final : public NativeFunction {
     JS_OBJECT(FunctionConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(FunctionConstructor);
 
diff --git a/Libraries/LibJS/Runtime/FunctionEnvironment.h b/Libraries/LibJS/Runtime/FunctionEnvironment.h
index ff72a29575a..55d82ae1794 100644
--- a/Libraries/LibJS/Runtime/FunctionEnvironment.h
+++ b/Libraries/LibJS/Runtime/FunctionEnvironment.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class FunctionEnvironment final : public DeclarativeEnvironment {
+class JS_API FunctionEnvironment final : public DeclarativeEnvironment {
     JS_ENVIRONMENT(FunctionEnvironment, DeclarativeEnvironment);
     GC_DECLARE_ALLOCATOR(FunctionEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/FunctionObject.h b/Libraries/LibJS/Runtime/FunctionObject.h
index e7ba55d5385..04ae1070332 100644
--- a/Libraries/LibJS/Runtime/FunctionObject.h
+++ b/Libraries/LibJS/Runtime/FunctionObject.h
@@ -16,7 +16,7 @@
 
 namespace JS {
 
-class FunctionObject : public Object {
+class JS_API FunctionObject : public Object {
     JS_OBJECT(FunctionObject, Object);
 
 public:
diff --git a/Libraries/LibJS/Runtime/FunctionPrototype.h b/Libraries/LibJS/Runtime/FunctionPrototype.h
index d56b755dc50..1ad0a3b4626 100644
--- a/Libraries/LibJS/Runtime/FunctionPrototype.h
+++ b/Libraries/LibJS/Runtime/FunctionPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class FunctionPrototype final : public FunctionObject {
+class JS_API FunctionPrototype final : public FunctionObject {
     JS_OBJECT(FunctionPrototype, FunctionObject);
     GC_DECLARE_ALLOCATOR(FunctionPrototype);
 
diff --git a/Libraries/LibJS/Runtime/GeneratorFunctionConstructor.h b/Libraries/LibJS/Runtime/GeneratorFunctionConstructor.h
index 17fa5d8213f..51420a80f74 100644
--- a/Libraries/LibJS/Runtime/GeneratorFunctionConstructor.h
+++ b/Libraries/LibJS/Runtime/GeneratorFunctionConstructor.h
@@ -11,7 +11,7 @@
 namespace JS {
 
 // 27.3.1 %GeneratorFunction%, https://tc39.es/ecma262/#sec-generatorfunction-constructor
-class GeneratorFunctionConstructor final : public NativeFunction {
+class JS_API GeneratorFunctionConstructor final : public NativeFunction {
     JS_OBJECT(GeneratorFunctionConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(GeneratorFunctionConstructor);
 
diff --git a/Libraries/LibJS/Runtime/GeneratorFunctionPrototype.h b/Libraries/LibJS/Runtime/GeneratorFunctionPrototype.h
index 48d71d99206..d5f841db199 100644
--- a/Libraries/LibJS/Runtime/GeneratorFunctionPrototype.h
+++ b/Libraries/LibJS/Runtime/GeneratorFunctionPrototype.h
@@ -12,7 +12,7 @@
 namespace JS {
 
 // 27.3.3 %GeneratorFunction.prototype%, https://tc39.es/ecma262/#sec-properties-of-the-generatorfunction-prototype-object
-class GeneratorFunctionPrototype final : public Object {
+class JS_API GeneratorFunctionPrototype final : public Object {
     JS_OBJECT(GeneratorFunctionPrototype, Object);
     GC_DECLARE_ALLOCATOR(GeneratorFunctionPrototype);
 
diff --git a/Libraries/LibJS/Runtime/GeneratorObject.h b/Libraries/LibJS/Runtime/GeneratorObject.h
index 39286d932aa..5eaf4b594e7 100644
--- a/Libraries/LibJS/Runtime/GeneratorObject.h
+++ b/Libraries/LibJS/Runtime/GeneratorObject.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class GeneratorObject : public Object {
+class JS_API GeneratorObject : public Object {
     JS_OBJECT(GeneratorObject, Object);
     GC_DECLARE_ALLOCATOR(GeneratorObject);
 
diff --git a/Libraries/LibJS/Runtime/GeneratorPrototype.h b/Libraries/LibJS/Runtime/GeneratorPrototype.h
index 1412008cb0f..05de9bc0aec 100644
--- a/Libraries/LibJS/Runtime/GeneratorPrototype.h
+++ b/Libraries/LibJS/Runtime/GeneratorPrototype.h
@@ -12,7 +12,7 @@
 namespace JS {
 
 // 27.5.1 Properties of the Generator Prototype Object, https://tc39.es/ecma262/#sec-properties-of-generator-prototype
-class GeneratorPrototype final : public PrototypeObject<GeneratorPrototype, GeneratorObject> {
+class JS_API GeneratorPrototype final : public PrototypeObject<GeneratorPrototype, GeneratorObject> {
     JS_PROTOTYPE_OBJECT(GeneratorPrototype, GeneratorObject, Generator);
     GC_DECLARE_ALLOCATOR(GeneratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/GeneratorResult.h b/Libraries/LibJS/Runtime/GeneratorResult.h
index 4c3c6ea0458..f28d797bf80 100644
--- a/Libraries/LibJS/Runtime/GeneratorResult.h
+++ b/Libraries/LibJS/Runtime/GeneratorResult.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class GeneratorResult final : public Cell {
+class JS_API GeneratorResult final : public Cell {
     GC_CELL(GeneratorResult, Cell);
     GC_DECLARE_ALLOCATOR(GeneratorResult);
 
diff --git a/Libraries/LibJS/Runtime/GlobalEnvironment.h b/Libraries/LibJS/Runtime/GlobalEnvironment.h
index 4008cf53218..0de5dcf3c48 100644
--- a/Libraries/LibJS/Runtime/GlobalEnvironment.h
+++ b/Libraries/LibJS/Runtime/GlobalEnvironment.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class GlobalEnvironment final : public Environment {
+class JS_API GlobalEnvironment final : public Environment {
     JS_ENVIRONMENT(GlobalEnvironment, Environment);
     GC_DECLARE_ALLOCATOR(GlobalEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/GlobalObject.h b/Libraries/LibJS/Runtime/GlobalObject.h
index d21e4839e82..e7c8422df01 100644
--- a/Libraries/LibJS/Runtime/GlobalObject.h
+++ b/Libraries/LibJS/Runtime/GlobalObject.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class GlobalObject : public Object {
+class JS_API GlobalObject : public Object {
     JS_OBJECT(GlobalObject, Object);
     GC_DECLARE_ALLOCATOR(GlobalObject);
 
@@ -43,7 +43,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(unescape);
 };
 
-void set_default_global_bindings(Realm&);
+JS_API void set_default_global_bindings(Realm&);
 
 template<>
 inline bool Object::fast_is<GlobalObject>() const { return is_global_object(); }
diff --git a/Libraries/LibJS/Runtime/IndexedProperties.h b/Libraries/LibJS/Runtime/IndexedProperties.h
index 51c82e081d6..e82a0f37f14 100644
--- a/Libraries/LibJS/Runtime/IndexedProperties.h
+++ b/Libraries/LibJS/Runtime/IndexedProperties.h
@@ -23,7 +23,7 @@ class IndexedProperties;
 class IndexedPropertyIterator;
 class GenericIndexedPropertyStorage;
 
-class IndexedPropertyStorage {
+class JS_API IndexedPropertyStorage {
 public:
     virtual ~IndexedPropertyStorage() = default;
 
@@ -59,7 +59,7 @@ private:
     bool m_is_simple_storage { false };
 };
 
-class SimpleIndexedPropertyStorage final : public IndexedPropertyStorage {
+class JS_API SimpleIndexedPropertyStorage final : public IndexedPropertyStorage {
 public:
     SimpleIndexedPropertyStorage()
         : IndexedPropertyStorage(IsSimpleStorage::Yes)
@@ -103,7 +103,7 @@ private:
     Vector<Value> m_packed_elements;
 };
 
-class GenericIndexedPropertyStorage final : public IndexedPropertyStorage {
+class JS_API GenericIndexedPropertyStorage final : public IndexedPropertyStorage {
 public:
     explicit GenericIndexedPropertyStorage(SimpleIndexedPropertyStorage&&);
     explicit GenericIndexedPropertyStorage()
@@ -128,7 +128,7 @@ private:
     HashMap<u32, ValueAndAttributes> m_sparse_elements;
 };
 
-class IndexedPropertyIterator {
+class JS_API IndexedPropertyIterator {
 public:
     IndexedPropertyIterator(IndexedProperties const&, u32 starting_index, bool skip_empty);
 
@@ -148,7 +148,7 @@ private:
     bool m_skip_empty { false };
 };
 
-class IndexedProperties {
+class JS_API IndexedProperties {
 public:
     IndexedProperties() = default;
 
diff --git a/Libraries/LibJS/Runtime/Intl/AbstractOperations.h b/Libraries/LibJS/Runtime/Intl/AbstractOperations.h
index 96880f40d56..6fb5b719608 100644
--- a/Libraries/LibJS/Runtime/Intl/AbstractOperations.h
+++ b/Libraries/LibJS/Runtime/Intl/AbstractOperations.h
@@ -63,23 +63,23 @@ AK_ENUM_BITWISE_OPERATORS(SpecialBehaviors);
 
 using StringOrBoolean = Variant<StringView, bool>;
 
-bool is_structurally_valid_language_tag(StringView locale);
-String canonicalize_unicode_locale_id(StringView locale);
-bool is_well_formed_currency_code(StringView currency);
-Vector<TimeZoneIdentifier> const& available_named_time_zone_identifiers();
-Optional<TimeZoneIdentifier const&> get_available_named_time_zone_identifier(StringView time_zone_identifier);
-bool is_well_formed_unit_identifier(StringView unit_identifier);
-ThrowCompletionOr<Vector<String>> canonicalize_locale_list(VM&, Value locales);
-Optional<MatchedLocale> lookup_matching_locale_by_prefix(ReadonlySpan<String> requested_locales);
-Optional<MatchedLocale> lookup_matching_locale_by_best_fit(ReadonlySpan<String> requested_locales);
-String insert_unicode_extension_and_canonicalize(Unicode::LocaleID locale_id, Vector<String> attributes, Vector<Unicode::Keyword> keywords);
-ResolvedLocale resolve_locale(ReadonlySpan<String> requested_locales, LocaleOptions const& options, ReadonlySpan<StringView> relevant_extension_keys);
-ThrowCompletionOr<ResolvedOptions> resolve_options(VM& vm, IntlObject& object, Value locales, Value options_value, SpecialBehaviors special_behaviours = SpecialBehaviors::None, Function<void(LocaleOptions&)> modify_resolution_options = {});
-ThrowCompletionOr<GC::Ref<Array>> filter_locales(VM& vm, ReadonlySpan<String> requested_locales, Value options);
-ThrowCompletionOr<GC::Ref<Object>> coerce_options_to_object(VM&, Value options);
-ThrowCompletionOr<StringOrBoolean> get_boolean_or_string_number_format_option(VM& vm, Object const& options, PropertyKey const& property, ReadonlySpan<StringView> string_values, StringOrBoolean fallback);
-ThrowCompletionOr<Optional<int>> default_number_option(VM&, Value value, int minimum, int maximum, Optional<int> fallback);
-ThrowCompletionOr<Optional<int>> get_number_option(VM&, Object const& options, PropertyKey const& property, int minimum, int maximum, Optional<int> fallback);
+JS_API bool is_structurally_valid_language_tag(StringView locale);
+JS_API String canonicalize_unicode_locale_id(StringView locale);
+JS_API bool is_well_formed_currency_code(StringView currency);
+JS_API Vector<TimeZoneIdentifier> const& available_named_time_zone_identifiers();
+JS_API Optional<TimeZoneIdentifier const&> get_available_named_time_zone_identifier(StringView time_zone_identifier);
+JS_API bool is_well_formed_unit_identifier(StringView unit_identifier);
+JS_API ThrowCompletionOr<Vector<String>> canonicalize_locale_list(VM&, Value locales);
+JS_API Optional<MatchedLocale> lookup_matching_locale_by_prefix(ReadonlySpan<String> requested_locales);
+JS_API Optional<MatchedLocale> lookup_matching_locale_by_best_fit(ReadonlySpan<String> requested_locales);
+JS_API String insert_unicode_extension_and_canonicalize(Unicode::LocaleID locale_id, Vector<String> attributes, Vector<Unicode::Keyword> keywords);
+JS_API ResolvedLocale resolve_locale(ReadonlySpan<String> requested_locales, LocaleOptions const& options, ReadonlySpan<StringView> relevant_extension_keys);
+JS_API ThrowCompletionOr<ResolvedOptions> resolve_options(VM& vm, IntlObject& object, Value locales, Value options_value, SpecialBehaviors special_behaviours = SpecialBehaviors::None, Function<void(LocaleOptions&)> modify_resolution_options = {});
+JS_API ThrowCompletionOr<GC::Ref<Array>> filter_locales(VM& vm, ReadonlySpan<String> requested_locales, Value options);
+JS_API ThrowCompletionOr<GC::Ref<Object>> coerce_options_to_object(VM&, Value options);
+JS_API ThrowCompletionOr<StringOrBoolean> get_boolean_or_string_number_format_option(VM& vm, Object const& options, PropertyKey const& property, ReadonlySpan<StringView> string_values, StringOrBoolean fallback);
+JS_API ThrowCompletionOr<Optional<int>> default_number_option(VM&, Value value, int minimum, int maximum, Optional<int> fallback);
+JS_API ThrowCompletionOr<Optional<int>> get_number_option(VM&, Object const& options, PropertyKey const& property, int minimum, int maximum, Optional<int> fallback);
 
 template<size_t Size>
 ThrowCompletionOr<StringOrBoolean> get_boolean_or_string_number_format_option(VM& vm, Object const& options, PropertyKey const& property, StringView const (&string_values)[Size], StringOrBoolean fallback)
diff --git a/Libraries/LibJS/Runtime/Intl/Collator.h b/Libraries/LibJS/Runtime/Intl/Collator.h
index d7b86f8ef61..0a8baea9c13 100644
--- a/Libraries/LibJS/Runtime/Intl/Collator.h
+++ b/Libraries/LibJS/Runtime/Intl/Collator.h
@@ -14,7 +14,7 @@
 
 namespace JS::Intl {
 
-class Collator final : public IntlObject {
+class JS_API Collator final : public IntlObject {
     JS_OBJECT(Collator, IntlObject);
     GC_DECLARE_ALLOCATOR(Collator);
 
diff --git a/Libraries/LibJS/Runtime/Intl/CollatorCompareFunction.h b/Libraries/LibJS/Runtime/Intl/CollatorCompareFunction.h
index 8be16f2fbf2..08e93503be1 100644
--- a/Libraries/LibJS/Runtime/Intl/CollatorCompareFunction.h
+++ b/Libraries/LibJS/Runtime/Intl/CollatorCompareFunction.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class CollatorCompareFunction : public NativeFunction {
+class JS_API CollatorCompareFunction : public NativeFunction {
     JS_OBJECT(CollatorCompareFunction, NativeFunction);
     GC_DECLARE_ALLOCATOR(CollatorCompareFunction);
 
@@ -30,6 +30,6 @@ private:
     GC::Ref<Collator> m_collator; // [[Collator]]
 };
 
-int compare_strings(Collator const&, StringView x, StringView y);
+JS_API int compare_strings(Collator const&, StringView x, StringView y);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intl/CollatorConstructor.h b/Libraries/LibJS/Runtime/Intl/CollatorConstructor.h
index 19b46921bca..c7c4107fd02 100644
--- a/Libraries/LibJS/Runtime/Intl/CollatorConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/CollatorConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class CollatorConstructor final : public NativeFunction {
+class JS_API CollatorConstructor final : public NativeFunction {
     JS_OBJECT(CollatorConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(CollatorConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/CollatorPrototype.h b/Libraries/LibJS/Runtime/Intl/CollatorPrototype.h
index 0caf3b03d0b..8352b497b28 100644
--- a/Libraries/LibJS/Runtime/Intl/CollatorPrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/CollatorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class CollatorPrototype final : public PrototypeObject<CollatorPrototype, Collator> {
+class JS_API CollatorPrototype final : public PrototypeObject<CollatorPrototype, Collator> {
     JS_PROTOTYPE_OBJECT(CollatorPrototype, Collator, Collator);
     GC_DECLARE_ALLOCATOR(CollatorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DateTimeFormat.h b/Libraries/LibJS/Runtime/Intl/DateTimeFormat.h
index 1968a37f197..c31d087d07a 100644
--- a/Libraries/LibJS/Runtime/Intl/DateTimeFormat.h
+++ b/Libraries/LibJS/Runtime/Intl/DateTimeFormat.h
@@ -19,7 +19,7 @@
 
 namespace JS::Intl {
 
-class DateTimeFormat final : public IntlObject {
+class JS_API DateTimeFormat final : public IntlObject {
     JS_OBJECT(DateTimeFormat, IntlObject);
     GC_DECLARE_ALLOCATOR(DateTimeFormat);
 
@@ -135,27 +135,27 @@ struct ValueFormat {
     double epoch_milliseconds { 0 };          // [[EpochNanoseconds]]
 };
 
-Vector<Unicode::DateTimeFormat::Partition> format_date_time_pattern(ValueFormat const&);
-ThrowCompletionOr<Vector<Unicode::DateTimeFormat::Partition>> partition_date_time_pattern(VM&, DateTimeFormat&, FormattableDateTime const&);
-ThrowCompletionOr<String> format_date_time(VM&, DateTimeFormat&, FormattableDateTime const&);
-ThrowCompletionOr<GC::Ref<Array>> format_date_time_to_parts(VM&, DateTimeFormat&, FormattableDateTime const&);
-ThrowCompletionOr<Vector<Unicode::DateTimeFormat::Partition>> partition_date_time_range_pattern(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
-ThrowCompletionOr<String> format_date_time_range(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
-ThrowCompletionOr<GC::Ref<Array>> format_date_time_range_to_parts(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
+JS_API Vector<Unicode::DateTimeFormat::Partition> format_date_time_pattern(ValueFormat const&);
+JS_API ThrowCompletionOr<Vector<Unicode::DateTimeFormat::Partition>> partition_date_time_pattern(VM&, DateTimeFormat&, FormattableDateTime const&);
+JS_API ThrowCompletionOr<String> format_date_time(VM&, DateTimeFormat&, FormattableDateTime const&);
+JS_API ThrowCompletionOr<GC::Ref<Array>> format_date_time_to_parts(VM&, DateTimeFormat&, FormattableDateTime const&);
+JS_API ThrowCompletionOr<Vector<Unicode::DateTimeFormat::Partition>> partition_date_time_range_pattern(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
+JS_API ThrowCompletionOr<String> format_date_time_range(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
+JS_API ThrowCompletionOr<GC::Ref<Array>> format_date_time_range_to_parts(VM&, DateTimeFormat&, FormattableDateTime const& start, FormattableDateTime const& end);
 
-Optional<Unicode::CalendarPattern> get_date_time_format(Unicode::CalendarPattern const& options, OptionRequired, OptionDefaults, OptionInherit);
-Unicode::CalendarPattern adjust_date_time_style_format(Unicode::CalendarPattern const& base_format, ReadonlySpan<Unicode::CalendarPattern::Field> allowed_options);
-ThrowCompletionOr<FormattableDateTime> to_date_time_formattable(VM&, Value);
-bool is_temporal_object(FormattableDateTime const&);
-bool same_temporal_type(FormattableDateTime const&, FormattableDateTime const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_temporal_date(VM&, DateTimeFormat&, Temporal::PlainDate const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_temporal_year_month(VM&, DateTimeFormat&, Temporal::PlainYearMonth const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_temporal_month_day(VM&, DateTimeFormat&, Temporal::PlainMonthDay const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_temporal_time(VM&, DateTimeFormat&, Temporal::PlainTime const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_temporal_date_time(VM&, DateTimeFormat&, Temporal::PlainDateTime const&);
-ValueFormat handle_date_time_temporal_instant(DateTimeFormat&, Temporal::Instant const&);
-ThrowCompletionOr<ValueFormat> handle_date_time_others(VM&, DateTimeFormat&, double);
-ThrowCompletionOr<ValueFormat> handle_date_time_value(VM&, DateTimeFormat&, FormattableDateTime const&);
+JS_API Optional<Unicode::CalendarPattern> get_date_time_format(Unicode::CalendarPattern const& options, OptionRequired, OptionDefaults, OptionInherit);
+JS_API Unicode::CalendarPattern adjust_date_time_style_format(Unicode::CalendarPattern const& base_format, ReadonlySpan<Unicode::CalendarPattern::Field> allowed_options);
+JS_API ThrowCompletionOr<FormattableDateTime> to_date_time_formattable(VM&, Value);
+JS_API bool is_temporal_object(FormattableDateTime const&);
+JS_API bool same_temporal_type(FormattableDateTime const&, FormattableDateTime const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_temporal_date(VM&, DateTimeFormat&, Temporal::PlainDate const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_temporal_year_month(VM&, DateTimeFormat&, Temporal::PlainYearMonth const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_temporal_month_day(VM&, DateTimeFormat&, Temporal::PlainMonthDay const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_temporal_time(VM&, DateTimeFormat&, Temporal::PlainTime const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_temporal_date_time(VM&, DateTimeFormat&, Temporal::PlainDateTime const&);
+JS_API ValueFormat handle_date_time_temporal_instant(DateTimeFormat&, Temporal::Instant const&);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_others(VM&, DateTimeFormat&, double);
+JS_API ThrowCompletionOr<ValueFormat> handle_date_time_value(VM&, DateTimeFormat&, FormattableDateTime const&);
 
 template<typename Callback>
 ThrowCompletionOr<void> for_each_calendar_field(VM& vm, Unicode::CalendarPattern& pattern, Callback&& callback)
diff --git a/Libraries/LibJS/Runtime/Intl/DateTimeFormatConstructor.h b/Libraries/LibJS/Runtime/Intl/DateTimeFormatConstructor.h
index 1890f8926bc..53161b1a327 100644
--- a/Libraries/LibJS/Runtime/Intl/DateTimeFormatConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/DateTimeFormatConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class DateTimeFormatConstructor final : public NativeFunction {
+class JS_API DateTimeFormatConstructor final : public NativeFunction {
     JS_OBJECT(DateTimeFormatConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DateTimeFormatConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DateTimeFormatFunction.h b/Libraries/LibJS/Runtime/Intl/DateTimeFormatFunction.h
index 53298ec50ee..0cb78a3e436 100644
--- a/Libraries/LibJS/Runtime/Intl/DateTimeFormatFunction.h
+++ b/Libraries/LibJS/Runtime/Intl/DateTimeFormatFunction.h
@@ -12,7 +12,7 @@
 
 namespace JS::Intl {
 
-class DateTimeFormatFunction final : public NativeFunction {
+class JS_API DateTimeFormatFunction final : public NativeFunction {
     JS_OBJECT(DateTimeFormatFunction, NativeFunction);
     GC_DECLARE_ALLOCATOR(DateTimeFormatFunction);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DateTimeFormatPrototype.h b/Libraries/LibJS/Runtime/Intl/DateTimeFormatPrototype.h
index bd302f79d9b..009262ff3a7 100644
--- a/Libraries/LibJS/Runtime/Intl/DateTimeFormatPrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/DateTimeFormatPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class DateTimeFormatPrototype final : public PrototypeObject<DateTimeFormatPrototype, DateTimeFormat> {
+class JS_API DateTimeFormatPrototype final : public PrototypeObject<DateTimeFormatPrototype, DateTimeFormat> {
     JS_PROTOTYPE_OBJECT(DateTimeFormatPrototype, DateTimeFormat, Intl.DateTimeFormat);
     GC_DECLARE_ALLOCATOR(DateTimeFormatPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DisplayNames.h b/Libraries/LibJS/Runtime/Intl/DisplayNames.h
index 371c5a85b1f..e4bb1df4a75 100644
--- a/Libraries/LibJS/Runtime/Intl/DisplayNames.h
+++ b/Libraries/LibJS/Runtime/Intl/DisplayNames.h
@@ -15,7 +15,7 @@
 
 namespace JS::Intl {
 
-class DisplayNames final : public IntlObject {
+class JS_API DisplayNames final : public IntlObject {
     JS_OBJECT(DisplayNames, IntlObject);
     GC_DECLARE_ALLOCATOR(DisplayNames);
 
@@ -71,7 +71,7 @@ private:
     Optional<Unicode::LanguageDisplay> m_language_display; // [[LanguageDisplay]]
 };
 
-ThrowCompletionOr<Value> canonical_code_for_display_names(VM&, DisplayNames::Type, StringView code);
-bool is_valid_date_time_field_code(StringView field);
+JS_API ThrowCompletionOr<Value> canonical_code_for_display_names(VM&, DisplayNames::Type, StringView code);
+JS_API bool is_valid_date_time_field_code(StringView field);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intl/DisplayNamesConstructor.h b/Libraries/LibJS/Runtime/Intl/DisplayNamesConstructor.h
index e9daabcd3f7..8206d4e2d87 100644
--- a/Libraries/LibJS/Runtime/Intl/DisplayNamesConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/DisplayNamesConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class DisplayNamesConstructor final : public NativeFunction {
+class JS_API DisplayNamesConstructor final : public NativeFunction {
     JS_OBJECT(DisplayNamesConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DisplayNamesConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.h b/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.h
index 54a63e7956b..de9e2a31a8e 100644
--- a/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/DisplayNamesPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class DisplayNamesPrototype final : public PrototypeObject<DisplayNamesPrototype, DisplayNames> {
+class JS_API DisplayNamesPrototype final : public PrototypeObject<DisplayNamesPrototype, DisplayNames> {
     JS_PROTOTYPE_OBJECT(DisplayNamesPrototype, DisplayNames, Intl.DisplayNames);
     GC_DECLARE_ALLOCATOR(DisplayNamesPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DurationFormat.h b/Libraries/LibJS/Runtime/Intl/DurationFormat.h
index d11fc96e1af..110ae594970 100644
--- a/Libraries/LibJS/Runtime/Intl/DurationFormat.h
+++ b/Libraries/LibJS/Runtime/Intl/DurationFormat.h
@@ -16,7 +16,7 @@
 
 namespace JS::Intl {
 
-class DurationFormat final : public IntlObject {
+class JS_API DurationFormat final : public IntlObject {
     JS_OBJECT(DurationFormat, IntlObject);
     GC_DECLARE_ALLOCATOR(DurationFormat);
 
@@ -66,7 +66,7 @@ public:
     };
 
     // 13.5.6.1 Duration Unit Options Records, https://tc39.es/ecma402/#sec-durationformat-unit-options-record
-    struct DurationUnitOptions {
+    struct JS_API DurationUnitOptions {
         ValueStyle style { ValueStyle::Long };
         Display display { Display::Auto };
     };
@@ -148,7 +148,7 @@ private:
     Optional<u8> m_fractional_digits;           // [[FractionalDigits]]
 };
 
-struct DurationInstanceComponent {
+struct JS_API DurationInstanceComponent {
     double (Temporal::Duration::*value_slot)() const;
     DurationFormat::DurationUnitOptions (DurationFormat::*get_internal_slot)() const;
     void (DurationFormat::*set_internal_slot)(DurationFormat::DurationUnitOptions);
@@ -176,21 +176,21 @@ static constexpr auto duration_instances_components = to_array<DurationInstanceC
     { &Temporal::Duration::nanoseconds, &DurationFormat::nanoseconds_options, &DurationFormat::set_nanoseconds_options, DurationFormat::Unit::Nanoseconds, sub_second_styles, DurationFormat::ValueStyle::Numeric },
 });
 
-struct DurationFormatPart {
+struct JS_API DurationFormatPart {
     StringView type;
     String value;
     StringView unit;
 };
 
-ThrowCompletionOr<DurationFormat::DurationUnitOptions> get_duration_unit_options(VM&, DurationFormat::Unit unit, Object const& options, DurationFormat::Style base_style, ReadonlySpan<StringView> styles_list, DurationFormat::ValueStyle digital_base, Optional<DurationFormat::ValueStyle> previous_style, bool two_digit_hours);
-Crypto::BigFraction compute_fractional_digits(DurationFormat const&, Temporal::Duration const&);
-bool next_unit_fractional(DurationFormat const&, DurationFormat::Unit unit);
-Vector<DurationFormatPart> format_numeric_hours(VM&, DurationFormat const&, MathematicalValue const& hours_value, bool sign_displayed);
-Vector<DurationFormatPart> format_numeric_minutes(VM&, DurationFormat const&, MathematicalValue const& minutes_value, bool hours_displayed, bool sign_displayed);
-Vector<DurationFormatPart> format_numeric_seconds(VM&, DurationFormat const&, MathematicalValue const& seconds_value, bool minutes_displayed, bool sign_displayed);
-Vector<DurationFormatPart> format_numeric_units(VM&, DurationFormat const&, Temporal::Duration const&, DurationFormat::Unit first_numeric_unit, bool sign_displayed);
-bool is_fractional_second_unit_name(DurationFormat::Unit);
-Vector<DurationFormatPart> list_format_parts(VM&, DurationFormat const&, Vector<Vector<DurationFormatPart>>& partitioned_parts_list);
-Vector<DurationFormatPart> partition_duration_format_pattern(VM&, DurationFormat const&, Temporal::Duration const&);
+JS_API ThrowCompletionOr<DurationFormat::DurationUnitOptions> get_duration_unit_options(VM&, DurationFormat::Unit unit, Object const& options, DurationFormat::Style base_style, ReadonlySpan<StringView> styles_list, DurationFormat::ValueStyle digital_base, Optional<DurationFormat::ValueStyle> previous_style, bool two_digit_hours);
+JS_API Crypto::BigFraction compute_fractional_digits(DurationFormat const&, Temporal::Duration const&);
+JS_API bool next_unit_fractional(DurationFormat const&, DurationFormat::Unit unit);
+JS_API Vector<DurationFormatPart> format_numeric_hours(VM&, DurationFormat const&, MathematicalValue const& hours_value, bool sign_displayed);
+JS_API Vector<DurationFormatPart> format_numeric_minutes(VM&, DurationFormat const&, MathematicalValue const& minutes_value, bool hours_displayed, bool sign_displayed);
+JS_API Vector<DurationFormatPart> format_numeric_seconds(VM&, DurationFormat const&, MathematicalValue const& seconds_value, bool minutes_displayed, bool sign_displayed);
+JS_API Vector<DurationFormatPart> format_numeric_units(VM&, DurationFormat const&, Temporal::Duration const&, DurationFormat::Unit first_numeric_unit, bool sign_displayed);
+JS_API bool is_fractional_second_unit_name(DurationFormat::Unit);
+JS_API Vector<DurationFormatPart> list_format_parts(VM&, DurationFormat const&, Vector<Vector<DurationFormatPart>>& partitioned_parts_list);
+JS_API Vector<DurationFormatPart> partition_duration_format_pattern(VM&, DurationFormat const&, Temporal::Duration const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.h b/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.h
index b67f8876f48..e5ea0a4a48d 100644
--- a/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class DurationFormatConstructor final : public NativeFunction {
+class JS_API DurationFormatConstructor final : public NativeFunction {
     JS_OBJECT(DurationFormatConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DurationFormatConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.h b/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.h
index 81f5d2d077c..2ea13b0c576 100644
--- a/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class DurationFormatPrototype final : public PrototypeObject<DurationFormatPrototype, DurationFormat> {
+class JS_API DurationFormatPrototype final : public PrototypeObject<DurationFormatPrototype, DurationFormat> {
     JS_PROTOTYPE_OBJECT(DurationFormatPrototype, DurationFormat, Intl.DurationFormat);
     GC_DECLARE_ALLOCATOR(DurationFormatPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/Intl.h b/Libraries/LibJS/Runtime/Intl/Intl.h
index ff48b384dd1..594fe993f72 100644
--- a/Libraries/LibJS/Runtime/Intl/Intl.h
+++ b/Libraries/LibJS/Runtime/Intl/Intl.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class Intl final : public Object {
+class JS_API Intl final : public Object {
     JS_OBJECT(Intl, Object);
     GC_DECLARE_ALLOCATOR(Intl);
 
diff --git a/Libraries/LibJS/Runtime/Intl/IntlObject.h b/Libraries/LibJS/Runtime/Intl/IntlObject.h
index 759113bee17..9627277759f 100644
--- a/Libraries/LibJS/Runtime/Intl/IntlObject.h
+++ b/Libraries/LibJS/Runtime/Intl/IntlObject.h
@@ -15,14 +15,14 @@
 namespace JS::Intl {
 
 // https://tc39.es/ecma402/#resolution-option-descriptor
-struct ResolutionOptionDescriptor {
+struct JS_API ResolutionOptionDescriptor {
     StringView key;
     PropertyKey property;
     OptionType type { OptionType::String };
     ReadonlySpan<StringView> values {};
 };
 
-class IntlObject : public Object {
+class JS_API IntlObject : public Object {
     JS_OBJECT(IntlObject, Object);
 
 public:
diff --git a/Libraries/LibJS/Runtime/Intl/ListFormat.h b/Libraries/LibJS/Runtime/Intl/ListFormat.h
index e1a392348b9..4f09f3dc332 100644
--- a/Libraries/LibJS/Runtime/Intl/ListFormat.h
+++ b/Libraries/LibJS/Runtime/Intl/ListFormat.h
@@ -15,7 +15,7 @@
 
 namespace JS::Intl {
 
-class ListFormat final : public IntlObject {
+class JS_API ListFormat final : public IntlObject {
     JS_OBJECT(ListFormat, IntlObject);
     GC_DECLARE_ALLOCATOR(ListFormat);
 
@@ -57,9 +57,9 @@ private:
     OwnPtr<Unicode::ListFormat> m_formatter;
 };
 
-Vector<Unicode::ListFormat::Partition> create_parts_from_list(ListFormat const&, ReadonlySpan<String> list);
-String format_list(ListFormat const&, ReadonlySpan<String> list);
-GC::Ref<Array> format_list_to_parts(VM&, ListFormat const&, ReadonlySpan<String> list);
-ThrowCompletionOr<Vector<String>> string_list_from_iterable(VM&, Value iterable);
+JS_API Vector<Unicode::ListFormat::Partition> create_parts_from_list(ListFormat const&, ReadonlySpan<String> list);
+JS_API String format_list(ListFormat const&, ReadonlySpan<String> list);
+JS_API GC::Ref<Array> format_list_to_parts(VM&, ListFormat const&, ReadonlySpan<String> list);
+JS_API ThrowCompletionOr<Vector<String>> string_list_from_iterable(VM&, Value iterable);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intl/ListFormatConstructor.h b/Libraries/LibJS/Runtime/Intl/ListFormatConstructor.h
index 0028e2b17f2..d80fba27cd4 100644
--- a/Libraries/LibJS/Runtime/Intl/ListFormatConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/ListFormatConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class ListFormatConstructor final : public NativeFunction {
+class JS_API ListFormatConstructor final : public NativeFunction {
     JS_OBJECT(ListFormatConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ListFormatConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/ListFormatPrototype.h b/Libraries/LibJS/Runtime/Intl/ListFormatPrototype.h
index 97fd29e3f82..03c74070cc8 100644
--- a/Libraries/LibJS/Runtime/Intl/ListFormatPrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/ListFormatPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class ListFormatPrototype final : public PrototypeObject<ListFormatPrototype, ListFormat> {
+class JS_API ListFormatPrototype final : public PrototypeObject<ListFormatPrototype, ListFormat> {
     JS_PROTOTYPE_OBJECT(ListFormatPrototype, ListFormat, Intl.ListFormat);
     GC_DECLARE_ALLOCATOR(ListFormatPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/Locale.h b/Libraries/LibJS/Runtime/Intl/Locale.h
index 9404905623e..c2c3a7557aa 100644
--- a/Libraries/LibJS/Runtime/Intl/Locale.h
+++ b/Libraries/LibJS/Runtime/Intl/Locale.h
@@ -18,7 +18,7 @@
 
 namespace JS::Intl {
 
-class Locale final : public Object {
+class JS_API Locale final : public Object {
     JS_OBJECT(Locale, Object);
     GC_DECLARE_ALLOCATOR(Locale);
 
@@ -85,21 +85,21 @@ private:
 };
 
 // Table 1: WeekInfo Record Fields, https://tc39.es/proposal-intl-locale-info/#table-locale-weekinfo-record
-struct WeekInfo {
+struct JS_API WeekInfo {
     u8 minimal_days { 0 }; // [[MinimalDays]]
     u8 first_day { 0 };    // [[FirstDay]]
     Vector<u8> weekend;    // [[Weekend]]
 };
 
-Optional<String> get_locale_variants(Unicode::LocaleID const&);
+JS_API Optional<String> get_locale_variants(Unicode::LocaleID const&);
 
-GC::Ref<Array> calendars_of_locale(VM&, Locale const&);
-GC::Ref<Array> collations_of_locale(VM&, Locale const& locale);
-GC::Ref<Array> hour_cycles_of_locale(VM&, Locale const& locale);
-GC::Ref<Array> numbering_systems_of_locale(VM&, Locale const&);
-GC::Ref<Array> time_zones_of_locale(VM&, Locale const&);
-StringView weekday_to_string(StringView weekday);
-Optional<u8> string_to_weekday_value(StringView weekday);
-WeekInfo week_info_of_locale(Locale const&);
+JS_API GC::Ref<Array> calendars_of_locale(VM&, Locale const&);
+JS_API GC::Ref<Array> collations_of_locale(VM&, Locale const& locale);
+JS_API GC::Ref<Array> hour_cycles_of_locale(VM&, Locale const& locale);
+JS_API GC::Ref<Array> numbering_systems_of_locale(VM&, Locale const&);
+JS_API GC::Ref<Array> time_zones_of_locale(VM&, Locale const&);
+JS_API StringView weekday_to_string(StringView weekday);
+JS_API Optional<u8> string_to_weekday_value(StringView weekday);
+JS_API WeekInfo week_info_of_locale(Locale const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intl/LocaleConstructor.h b/Libraries/LibJS/Runtime/Intl/LocaleConstructor.h
index 2829671d077..fd92f3e935d 100644
--- a/Libraries/LibJS/Runtime/Intl/LocaleConstructor.h
+++ b/Libraries/LibJS/Runtime/Intl/LocaleConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS::Intl {
 
-class LocaleConstructor final : public NativeFunction {
+class JS_API LocaleConstructor final : public NativeFunction {
     JS_OBJECT(LocaleConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(LocaleConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Intl/LocalePrototype.h b/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
index a0788c5d38b..32981d544d0 100644
--- a/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
+++ b/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS::Intl {
 
-class LocalePrototype final : public PrototypeObject<LocalePrototype, Locale> {
+class JS_API LocalePrototype final : public PrototypeObject<LocalePrototype, Locale> {
     JS_PROTOTYPE_OBJECT(LocalePrototype, Locale, Intl.Locale);
     GC_DECLARE_ALLOCATOR(LocalePrototype);
 
diff --git a/Libraries/LibJS/Runtime/Intl/MathematicalValue.h b/Libraries/LibJS/Runtime/Intl/MathematicalValue.h
index 0510f37c28c..6375fd8e0dd 100644
--- a/Libraries/LibJS/Runtime/Intl/MathematicalValue.h
+++ b/Libraries/LibJS/Runtime/Intl/MathematicalValue.h
@@ -16,7 +16,7 @@
 namespace JS::Intl {
 
 // https://tc39.es/ecma402/#intl-mathematical-value
-class MathematicalValue {
+class JS_API MathematicalValue {
 public:
     enum class Symbol {
         PositiveInfinity,
diff --git a/Libraries/LibJS/Runtime/Intl/NumberFormat.h b/Libraries/LibJS/Runtime/Intl/NumberFormat.h
index 8d1ab74515b..7a915cc08b3 100644
--- a/Libraries/LibJS/Runtime/Intl/NumberFormat.h
+++ b/Libraries/LibJS/Runtime/Intl/NumberFormat.h
@@ -16,7 +16,7 @@
 
 namespace JS::Intl {
 
-class NumberFormatBase : public IntlObject {
+class JS_API NumberFormatBase : public IntlObject {
     JS_OBJECT(NumberFormatBase, IntlObject);
     GC_DECLARE_ALLOCATOR(NumberFormatBase);
 
@@ -108,7 +108,7 @@ private:
     OwnPtr<Unicode::NumberFormat> m_formatter;
 };
 
-class NumberFormat final : public NumberFormatBase {
+class JS_API NumberFormat final : public NumberFormatBase {
     JS_OBJECT(NumberFormat, NumberFormatBase);
     GC_DECLARE_ALLOCATOR(NumberFormat);
 
@@ -179,14 +179,14 @@ private:
     GC::Ptr<NativeFunction> m_bound_format;                        // [[BoundFormat]]
 };
 
-int currency_digits(StringView currency);
-String format_numeric_to_string(NumberFormatBase const& intl_object, MathematicalValue const& number);
-Vector<Unicode::NumberFormat::Partition> partition_number_pattern(NumberFormat const&, MathematicalValue const& number);
-String format_numeric(NumberFormat const&, MathematicalValue const& number);
-GC::Ref<Array> format_numeric_to_parts(VM&, NumberFormat const&, MathematicalValue const& number);
-ThrowCompletionOr<MathematicalValue> to_intl_mathematical_value(VM&, Value value);
-ThrowCompletionOr<Vector<Unicode::NumberFormat::Partition>> partition_number_range_pattern(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
-ThrowCompletionOr<String> format_numeric_range(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
-ThrowCompletionOr<GC::Ref<Array>> format_numeric_range_to_parts(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
+JS_API int currency_digits(StringView currency);
+JS_API String format_numeric_to_string(NumberFormatBase const& intl_object, MathematicalValue const& number);
+JS_API Vector<Unicode::NumberFormat::Partition> partition_number_pattern(NumberFormat const&, MathematicalValue const& number);
+JS_API String format_numeric(NumberFormat const&, MathematicalValue const& number);
+JS_API GC::Ref<Array> format_numeric_to_parts(VM&, NumberFormat const&, MathematicalValue const& number);
+JS_API ThrowCompletionOr<MathematicalValue> to_intl_mathematical_value(VM&, Value value);
+JS_API ThrowCompletionOr<Vector<Unicode::NumberFormat::Partition>> partition_number_range_pattern(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
+JS_API ThrowCompletionOr<String> format_numeric_range(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
+JS_API ThrowCompletionOr<GC::Ref<Array>> format_numeric_range_to_parts(VM&, NumberFormat const&, MathematicalValue const& start, MathematicalValue const& end);
 
 }
diff --git a/Libraries/LibJS/Runtime/Intrinsics.h b/Libraries/LibJS/Runtime/Intrinsics.h
index 3f69abfa3f0..a451175cb73 100644
--- a/Libraries/LibJS/Runtime/Intrinsics.h
+++ b/Libraries/LibJS/Runtime/Intrinsics.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class Intrinsics final : public Cell {
+class JS_API Intrinsics final : public Cell {
     GC_CELL(Intrinsics, Cell);
     GC_DECLARE_ALLOCATOR(Intrinsics);
 
@@ -251,6 +251,6 @@ private:
     GC::Ptr<Intl::Collator> m_default_collator;
 };
 
-void add_restricted_function_properties(FunctionObject&, Realm&);
+JS_API void add_restricted_function_properties(FunctionObject&, Realm&);
 
 }
diff --git a/Libraries/LibJS/Runtime/Iterator.h b/Libraries/LibJS/Runtime/Iterator.h
index 3c480f1d10a..376dbdb3348 100644
--- a/Libraries/LibJS/Runtime/Iterator.h
+++ b/Libraries/LibJS/Runtime/Iterator.h
@@ -17,7 +17,7 @@
 namespace JS {
 
 // 7.4.1 Iterator Records, https://tc39.es/ecma262/#sec-iterator-records
-class IteratorRecord final : public Cell {
+class JS_API IteratorRecord final : public Cell {
     GC_CELL(IteratorRecord, Cell);
     GC_DECLARE_ALLOCATOR(IteratorRecord);
 
@@ -42,7 +42,7 @@ private:
 static_assert(sizeof(IteratorRecord) == 32);
 #endif
 
-class Iterator : public Object {
+class JS_API Iterator : public Object {
     JS_OBJECT(Iterator, Object);
     GC_DECLARE_ALLOCATOR(Iterator);
 
@@ -70,7 +70,7 @@ enum class PrimitiveHandling {
     RejectPrimitives,
 };
 
-class BuiltinIterator {
+class JS_API BuiltinIterator {
 public:
     virtual ~BuiltinIterator() = default;
     virtual ThrowCompletionOr<void> next(VM&, bool& done, Value& value) = 0;
@@ -101,22 +101,22 @@ using IterationResultOrDone = Variant<IterationResult, IterationDone>;
         _temporary_try_or_close_result.release_value();                                                           \
     })
 
-ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_direct(VM&, Object&);
-ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_from_method(VM&, Value, GC::Ref<FunctionObject>);
-ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator(VM&, Value, IteratorHint);
-ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_flattenable(VM&, Value, PrimitiveHandling);
-ThrowCompletionOr<GC::Ref<Object>> iterator_next(VM&, IteratorRecord&, Optional<Value> = {});
-ThrowCompletionOr<bool> iterator_complete(VM&, Object& iterator_result);
-ThrowCompletionOr<Value> iterator_value(VM&, Object& iterator_result);
-ThrowCompletionOr<IterationResultOrDone> iterator_step(VM&, IteratorRecord&);
-ThrowCompletionOr<Optional<Value>> iterator_step_value(VM&, IteratorRecord&);
-Completion iterator_close(VM&, IteratorRecord const&, Completion);
-Completion async_iterator_close(VM&, IteratorRecord const&, Completion);
-GC::Ref<Object> create_iterator_result_object(VM&, Value, bool done);
-ThrowCompletionOr<GC::RootVector<Value>> iterator_to_list(VM&, IteratorRecord&);
-ThrowCompletionOr<void> setter_that_ignores_prototype_properties(VM&, Value this_, Object const& home, PropertyKey const& property, Value value);
+JS_API ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_direct(VM&, Object&);
+JS_API ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_from_method(VM&, Value, GC::Ref<FunctionObject>);
+JS_API ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator(VM&, Value, IteratorHint);
+JS_API ThrowCompletionOr<GC::Ref<IteratorRecord>> get_iterator_flattenable(VM&, Value, PrimitiveHandling);
+JS_API ThrowCompletionOr<GC::Ref<Object>> iterator_next(VM&, IteratorRecord&, Optional<Value> = {});
+JS_API ThrowCompletionOr<bool> iterator_complete(VM&, Object& iterator_result);
+JS_API ThrowCompletionOr<Value> iterator_value(VM&, Object& iterator_result);
+JS_API ThrowCompletionOr<IterationResultOrDone> iterator_step(VM&, IteratorRecord&);
+JS_API ThrowCompletionOr<Optional<Value>> iterator_step_value(VM&, IteratorRecord&);
+JS_API Completion iterator_close(VM&, IteratorRecord const&, Completion);
+JS_API Completion async_iterator_close(VM&, IteratorRecord const&, Completion);
+JS_API GC::Ref<Object> create_iterator_result_object(VM&, Value, bool done);
+JS_API ThrowCompletionOr<GC::RootVector<Value>> iterator_to_list(VM&, IteratorRecord&);
+JS_API ThrowCompletionOr<void> setter_that_ignores_prototype_properties(VM&, Value this_, Object const& home, PropertyKey const& property, Value value);
 
 using IteratorValueCallback = Function<Optional<Completion>(Value)>;
-Completion get_iterator_values(VM&, Value iterable, IteratorValueCallback callback);
+JS_API Completion get_iterator_values(VM&, Value iterable, IteratorValueCallback callback);
 
 }
diff --git a/Libraries/LibJS/Runtime/IteratorConstructor.h b/Libraries/LibJS/Runtime/IteratorConstructor.h
index 88828f9019e..ecae698dcc1 100644
--- a/Libraries/LibJS/Runtime/IteratorConstructor.h
+++ b/Libraries/LibJS/Runtime/IteratorConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class IteratorConstructor : public NativeFunction {
+class JS_API IteratorConstructor : public NativeFunction {
     JS_OBJECT(IteratorConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(IteratorConstructor);
 
diff --git a/Libraries/LibJS/Runtime/IteratorHelper.h b/Libraries/LibJS/Runtime/IteratorHelper.h
index f7aee61ff14..7987954d786 100644
--- a/Libraries/LibJS/Runtime/IteratorHelper.h
+++ b/Libraries/LibJS/Runtime/IteratorHelper.h
@@ -14,7 +14,7 @@
 
 namespace JS {
 
-class IteratorHelper final : public GeneratorObject {
+class JS_API IteratorHelper final : public GeneratorObject {
     JS_OBJECT(IteratorHelper, GeneratorObject);
     GC_DECLARE_ALLOCATOR(IteratorHelper);
 
diff --git a/Libraries/LibJS/Runtime/IteratorHelperPrototype.h b/Libraries/LibJS/Runtime/IteratorHelperPrototype.h
index ee344bbbe51..800586f5f90 100644
--- a/Libraries/LibJS/Runtime/IteratorHelperPrototype.h
+++ b/Libraries/LibJS/Runtime/IteratorHelperPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class IteratorHelperPrototype final : public PrototypeObject<IteratorHelperPrototype, IteratorHelper> {
+class JS_API IteratorHelperPrototype final : public PrototypeObject<IteratorHelperPrototype, IteratorHelper> {
     JS_PROTOTYPE_OBJECT(IteratorHelperPrototype, IteratorHelper, IteratorHelper);
     GC_DECLARE_ALLOCATOR(IteratorHelperPrototype);
 
diff --git a/Libraries/LibJS/Runtime/IteratorPrototype.h b/Libraries/LibJS/Runtime/IteratorPrototype.h
index 11f1087ce5f..636709be503 100644
--- a/Libraries/LibJS/Runtime/IteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/IteratorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class IteratorPrototype : public PrototypeObject<IteratorPrototype, Iterator> {
+class JS_API IteratorPrototype : public PrototypeObject<IteratorPrototype, Iterator> {
     JS_PROTOTYPE_OBJECT(IteratorPrototype, Iterator, Iterator);
     GC_DECLARE_ALLOCATOR(IteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/JSONObject.h b/Libraries/LibJS/Runtime/JSONObject.h
index d390fbdfa30..0773ba2d7d1 100644
--- a/Libraries/LibJS/Runtime/JSONObject.h
+++ b/Libraries/LibJS/Runtime/JSONObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class JSONObject final : public Object {
+class JS_API JSONObject final : public Object {
     JS_OBJECT(JSONObject, Object);
     GC_DECLARE_ALLOCATOR(JSONObject);
 
diff --git a/Libraries/LibJS/Runtime/JobCallback.h b/Libraries/LibJS/Runtime/JobCallback.h
index 5279492a1ca..f3cf34a7a17 100644
--- a/Libraries/LibJS/Runtime/JobCallback.h
+++ b/Libraries/LibJS/Runtime/JobCallback.h
@@ -15,7 +15,7 @@
 namespace JS {
 
 // 9.5.1 JobCallback Records, https://tc39.es/ecma262/#sec-jobcallback-records
-class JobCallback : public JS::Cell {
+class JS_API JobCallback : public JS::Cell {
     GC_CELL(JobCallback, JS::Cell);
     GC_DECLARE_ALLOCATOR(JobCallback);
 
@@ -42,7 +42,7 @@ private:
     OwnPtr<CustomData> m_custom_data { nullptr };
 };
 
-GC::Ref<JobCallback> make_job_callback(FunctionObject& callback);
-ThrowCompletionOr<Value> call_job_callback(VM&, GC::Ref<JobCallback>, Value this_value, ReadonlySpan<Value> arguments_list);
+JS_API GC::Ref<JobCallback> make_job_callback(FunctionObject& callback);
+JS_API ThrowCompletionOr<Value> call_job_callback(VM&, GC::Ref<JobCallback>, Value this_value, ReadonlySpan<Value> arguments_list);
 
 }
diff --git a/Libraries/LibJS/Runtime/KeyedCollections.h b/Libraries/LibJS/Runtime/KeyedCollections.h
index f7f6b11d18c..d4b754f3ce4 100644
--- a/Libraries/LibJS/Runtime/KeyedCollections.h
+++ b/Libraries/LibJS/Runtime/KeyedCollections.h
@@ -10,6 +10,6 @@
 
 namespace JS {
 
-Value canonicalize_keyed_collection_key(Value);
+JS_API Value canonicalize_keyed_collection_key(Value);
 
 }
diff --git a/Libraries/LibJS/Runtime/Map.h b/Libraries/LibJS/Runtime/Map.h
index bc020407c72..eb33edb91c3 100644
--- a/Libraries/LibJS/Runtime/Map.h
+++ b/Libraries/LibJS/Runtime/Map.h
@@ -15,7 +15,7 @@
 
 namespace JS {
 
-class Map : public Object {
+class JS_API Map : public Object {
     JS_OBJECT(Map, Object);
     GC_DECLARE_ALLOCATOR(Map);
 
diff --git a/Libraries/LibJS/Runtime/MapConstructor.h b/Libraries/LibJS/Runtime/MapConstructor.h
index ce9929bc5f1..01a6921ef65 100644
--- a/Libraries/LibJS/Runtime/MapConstructor.h
+++ b/Libraries/LibJS/Runtime/MapConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class MapConstructor final : public NativeFunction {
+class JS_API MapConstructor final : public NativeFunction {
     JS_OBJECT(MapConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(MapConstructor);
 
diff --git a/Libraries/LibJS/Runtime/MapIterator.h b/Libraries/LibJS/Runtime/MapIterator.h
index 1325a54999d..2c9affe0b7f 100644
--- a/Libraries/LibJS/Runtime/MapIterator.h
+++ b/Libraries/LibJS/Runtime/MapIterator.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class MapIterator final : public Object
+class JS_API MapIterator final : public Object
     , public BuiltinIterator {
     JS_OBJECT(MapIterator, Object);
     GC_DECLARE_ALLOCATOR(MapIterator);
diff --git a/Libraries/LibJS/Runtime/MapIteratorPrototype.h b/Libraries/LibJS/Runtime/MapIteratorPrototype.h
index a7663bf29f5..998f9408f84 100644
--- a/Libraries/LibJS/Runtime/MapIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/MapIteratorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class MapIteratorPrototype final : public PrototypeObject<MapIteratorPrototype, MapIterator> {
+class JS_API MapIteratorPrototype final : public PrototypeObject<MapIteratorPrototype, MapIterator> {
     JS_PROTOTYPE_OBJECT(MapIteratorPrototype, MapIterator, MapIterator);
     GC_DECLARE_ALLOCATOR(MapIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/MapPrototype.h b/Libraries/LibJS/Runtime/MapPrototype.h
index 5b241a3ece1..aeeb9311640 100644
--- a/Libraries/LibJS/Runtime/MapPrototype.h
+++ b/Libraries/LibJS/Runtime/MapPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class MapPrototype final : public PrototypeObject<MapPrototype, Map> {
+class JS_API MapPrototype final : public PrototypeObject<MapPrototype, Map> {
     JS_PROTOTYPE_OBJECT(MapPrototype, Map, Map);
     GC_DECLARE_ALLOCATOR(MapPrototype);
 
diff --git a/Libraries/LibJS/Runtime/MathObject.h b/Libraries/LibJS/Runtime/MathObject.h
index 99e9c52bca4..a1c43e9c3f5 100644
--- a/Libraries/LibJS/Runtime/MathObject.h
+++ b/Libraries/LibJS/Runtime/MathObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class MathObject final : public Object {
+class JS_API MathObject final : public Object {
     JS_OBJECT(MathObject, Object);
     GC_DECLARE_ALLOCATOR(MathObject);
 
diff --git a/Libraries/LibJS/Runtime/ModuleEnvironment.h b/Libraries/LibJS/Runtime/ModuleEnvironment.h
index daec2c0ca1d..21313577d70 100644
--- a/Libraries/LibJS/Runtime/ModuleEnvironment.h
+++ b/Libraries/LibJS/Runtime/ModuleEnvironment.h
@@ -13,7 +13,7 @@
 namespace JS {
 
 // 9.1.1.5 Module Environment Records, https://tc39.es/ecma262/#sec-module-environment-records
-class ModuleEnvironment final : public DeclarativeEnvironment {
+class JS_API ModuleEnvironment final : public DeclarativeEnvironment {
     JS_ENVIRONMENT(ModuleEnvironment, DeclarativeEnvironment);
     GC_DECLARE_ALLOCATOR(ModuleEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/ModuleNamespaceObject.h b/Libraries/LibJS/Runtime/ModuleNamespaceObject.h
index 81b56852f54..2fbdb01e475 100644
--- a/Libraries/LibJS/Runtime/ModuleNamespaceObject.h
+++ b/Libraries/LibJS/Runtime/ModuleNamespaceObject.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class ModuleNamespaceObject final : public Object {
+class JS_API ModuleNamespaceObject final : public Object {
     JS_OBJECT(ModuleNamespaceObject, Object);
     GC_DECLARE_ALLOCATOR(ModuleNamespaceObject);
 
diff --git a/Libraries/LibJS/Runtime/ModuleRequest.h b/Libraries/LibJS/Runtime/ModuleRequest.h
index 44f2d52a053..7d2a30d6604 100644
--- a/Libraries/LibJS/Runtime/ModuleRequest.h
+++ b/Libraries/LibJS/Runtime/ModuleRequest.h
@@ -27,7 +27,7 @@ struct ImportAttribute {
 };
 
 // https://tc39.es/ecma262/#modulerequest-record
-struct ModuleRequest {
+struct JS_API ModuleRequest {
     ModuleRequest() = default;
 
     explicit ModuleRequest(FlyString specifier)
diff --git a/Libraries/LibJS/Runtime/NativeFunction.h b/Libraries/LibJS/Runtime/NativeFunction.h
index 50c3b0629b3..edab84c0d7d 100644
--- a/Libraries/LibJS/Runtime/NativeFunction.h
+++ b/Libraries/LibJS/Runtime/NativeFunction.h
@@ -17,7 +17,7 @@
 
 namespace JS {
 
-class NativeFunction : public FunctionObject {
+class JS_API NativeFunction : public FunctionObject {
     JS_OBJECT(NativeFunction, FunctionObject);
     GC_DECLARE_ALLOCATOR(NativeFunction);
 
diff --git a/Libraries/LibJS/Runtime/NumberConstructor.h b/Libraries/LibJS/Runtime/NumberConstructor.h
index 9ed3331a296..2a76cbacb81 100644
--- a/Libraries/LibJS/Runtime/NumberConstructor.h
+++ b/Libraries/LibJS/Runtime/NumberConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class NumberConstructor final : public NativeFunction {
+class JS_API NumberConstructor final : public NativeFunction {
     JS_OBJECT(NumberConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(NumberConstructor);
 
diff --git a/Libraries/LibJS/Runtime/NumberObject.h b/Libraries/LibJS/Runtime/NumberObject.h
index dd4444d4742..31f2eadb90f 100644
--- a/Libraries/LibJS/Runtime/NumberObject.h
+++ b/Libraries/LibJS/Runtime/NumberObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class NumberObject : public Object {
+class JS_API NumberObject : public Object {
     JS_OBJECT(NumberObject, Object);
     GC_DECLARE_ALLOCATOR(NumberObject);
 
diff --git a/Libraries/LibJS/Runtime/NumberPrototype.h b/Libraries/LibJS/Runtime/NumberPrototype.h
index c8a79107cd5..bff54a4eccd 100644
--- a/Libraries/LibJS/Runtime/NumberPrototype.h
+++ b/Libraries/LibJS/Runtime/NumberPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class NumberPrototype final : public NumberObject {
+class JS_API NumberPrototype final : public NumberObject {
     JS_OBJECT(NumberPrototype, NumberObject);
     GC_DECLARE_ALLOCATOR(NumberPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Object.h b/Libraries/LibJS/Runtime/Object.h
index 8512a7bd430..a3a5cbb0060 100644
--- a/Libraries/LibJS/Runtime/Object.h
+++ b/Libraries/LibJS/Runtime/Object.h
@@ -51,7 +51,7 @@ struct CacheablePropertyMetadata {
     GC::Ptr<Object const> prototype;
 };
 
-class Object : public Cell
+class JS_API Object : public Cell
     , public Weakable<Object> {
     GC_CELL(Object, Cell);
     GC_DECLARE_ALLOCATOR(Object);
diff --git a/Libraries/LibJS/Runtime/ObjectConstructor.h b/Libraries/LibJS/Runtime/ObjectConstructor.h
index 6d2544f4874..a55812c24c7 100644
--- a/Libraries/LibJS/Runtime/ObjectConstructor.h
+++ b/Libraries/LibJS/Runtime/ObjectConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ObjectConstructor final : public NativeFunction {
+class JS_API ObjectConstructor final : public NativeFunction {
     JS_OBJECT(ObjectConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ObjectConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ObjectEnvironment.h b/Libraries/LibJS/Runtime/ObjectEnvironment.h
index 509f6675ab5..9bc7fb538b6 100644
--- a/Libraries/LibJS/Runtime/ObjectEnvironment.h
+++ b/Libraries/LibJS/Runtime/ObjectEnvironment.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ObjectEnvironment final : public Environment {
+class JS_API ObjectEnvironment final : public Environment {
     JS_ENVIRONMENT(ObjectEnvironment, Environment);
     GC_DECLARE_ALLOCATOR(ObjectEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/ObjectPrototype.h b/Libraries/LibJS/Runtime/ObjectPrototype.h
index 622b307b455..76292ea5b0e 100644
--- a/Libraries/LibJS/Runtime/ObjectPrototype.h
+++ b/Libraries/LibJS/Runtime/ObjectPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ObjectPrototype final : public Object {
+class JS_API ObjectPrototype final : public Object {
     JS_OBJECT(ObjectPrototype, Object);
     GC_DECLARE_ALLOCATOR(ObjectPrototype);
 
diff --git a/Libraries/LibJS/Runtime/PrimitiveString.h b/Libraries/LibJS/Runtime/PrimitiveString.h
index 3d7134bc1eb..d274ed4c356 100644
--- a/Libraries/LibJS/Runtime/PrimitiveString.h
+++ b/Libraries/LibJS/Runtime/PrimitiveString.h
@@ -19,7 +19,7 @@
 
 namespace JS {
 
-class PrimitiveString : public Cell {
+class JS_API PrimitiveString : public Cell {
     GC_CELL(PrimitiveString, Cell);
     GC_DECLARE_ALLOCATOR(PrimitiveString);
 
diff --git a/Libraries/LibJS/Runtime/PrivateEnvironment.h b/Libraries/LibJS/Runtime/PrivateEnvironment.h
index d79d6386cde..a3c9cff01ed 100644
--- a/Libraries/LibJS/Runtime/PrivateEnvironment.h
+++ b/Libraries/LibJS/Runtime/PrivateEnvironment.h
@@ -14,7 +14,7 @@
 
 namespace JS {
 
-struct PrivateName {
+struct JS_API PrivateName {
     PrivateName() = default;
     PrivateName(u64 unique_id, FlyString description)
         : unique_id(unique_id)
@@ -28,7 +28,7 @@ struct PrivateName {
     bool operator==(PrivateName const& rhs) const;
 };
 
-class PrivateEnvironment : public Cell {
+class JS_API PrivateEnvironment : public Cell {
     GC_CELL(PrivateEnvironment, Cell);
     GC_DECLARE_ALLOCATOR(PrivateEnvironment);
 
diff --git a/Libraries/LibJS/Runtime/Promise.h b/Libraries/LibJS/Runtime/Promise.h
index 13e3be9e160..1afeaac662d 100644
--- a/Libraries/LibJS/Runtime/Promise.h
+++ b/Libraries/LibJS/Runtime/Promise.h
@@ -13,7 +13,7 @@ namespace JS {
 
 ThrowCompletionOr<Object*> promise_resolve(VM&, Object& constructor, Value);
 
-class Promise : public Object {
+class JS_API Promise : public Object {
     JS_OBJECT(Promise, Object);
     GC_DECLARE_ALLOCATOR(Promise);
 
diff --git a/Libraries/LibJS/Runtime/PromiseCapability.h b/Libraries/LibJS/Runtime/PromiseCapability.h
index 7a405ea985c..8ec828b0634 100644
--- a/Libraries/LibJS/Runtime/PromiseCapability.h
+++ b/Libraries/LibJS/Runtime/PromiseCapability.h
@@ -13,7 +13,7 @@
 namespace JS {
 
 // 27.2.1.1 PromiseCapability Records, https://tc39.es/ecma262/#sec-promisecapability-records
-class PromiseCapability final : public Cell {
+class JS_API PromiseCapability final : public Cell {
     GC_CELL(PromiseCapability, Cell);
     GC_DECLARE_ALLOCATOR(PromiseCapability);
 
@@ -65,6 +65,6 @@ private:
     __TRY_OR_REJECT(vm, capability, expression, MUST)
 
 // 27.2.1.5 NewPromiseCapability ( C ), https://tc39.es/ecma262/#sec-newpromisecapability
-ThrowCompletionOr<GC::Ref<PromiseCapability>> new_promise_capability(VM& vm, Value constructor);
+JS_API ThrowCompletionOr<GC::Ref<PromiseCapability>> new_promise_capability(VM& vm, Value constructor);
 
 }
diff --git a/Libraries/LibJS/Runtime/PromiseConstructor.h b/Libraries/LibJS/Runtime/PromiseConstructor.h
index 0bee0122442..465582ee676 100644
--- a/Libraries/LibJS/Runtime/PromiseConstructor.h
+++ b/Libraries/LibJS/Runtime/PromiseConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class PromiseConstructor final : public NativeFunction {
+class JS_API PromiseConstructor final : public NativeFunction {
     JS_OBJECT(PromiseConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PromiseConstructor);
 
diff --git a/Libraries/LibJS/Runtime/PromiseJobs.h b/Libraries/LibJS/Runtime/PromiseJobs.h
index b44982d852c..a2b318573ac 100644
--- a/Libraries/LibJS/Runtime/PromiseJobs.h
+++ b/Libraries/LibJS/Runtime/PromiseJobs.h
@@ -20,7 +20,7 @@ struct PromiseJob {
 };
 
 // NOTE: These return a PromiseJob to prevent awkward casting at call sites.
-PromiseJob create_promise_reaction_job(VM&, PromiseReaction&, Value argument);
-PromiseJob create_promise_resolve_thenable_job(VM&, Promise&, Value thenable, GC::Ref<JobCallback> then);
+JS_API PromiseJob create_promise_reaction_job(VM&, PromiseReaction&, Value argument);
+JS_API PromiseJob create_promise_resolve_thenable_job(VM&, Promise&, Value thenable, GC::Ref<JobCallback> then);
 
 }
diff --git a/Libraries/LibJS/Runtime/PromisePrototype.h b/Libraries/LibJS/Runtime/PromisePrototype.h
index e547867524e..a3a8439720b 100644
--- a/Libraries/LibJS/Runtime/PromisePrototype.h
+++ b/Libraries/LibJS/Runtime/PromisePrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class PromisePrototype final : public PrototypeObject<PromisePrototype, Promise> {
+class JS_API PromisePrototype final : public PrototypeObject<PromisePrototype, Promise> {
     JS_PROTOTYPE_OBJECT(PromisePrototype, Promise, Promise);
     GC_DECLARE_ALLOCATOR(PromisePrototype);
 
diff --git a/Libraries/LibJS/Runtime/PromiseReaction.h b/Libraries/LibJS/Runtime/PromiseReaction.h
index 6f51990244a..546cf452223 100644
--- a/Libraries/LibJS/Runtime/PromiseReaction.h
+++ b/Libraries/LibJS/Runtime/PromiseReaction.h
@@ -14,7 +14,7 @@
 namespace JS {
 
 // 27.2.1.2 PromiseReaction Records, https://tc39.es/ecma262/#sec-promisereaction-records
-class PromiseReaction final : public Cell {
+class JS_API PromiseReaction final : public Cell {
     GC_CELL(PromiseReaction, Cell);
     GC_DECLARE_ALLOCATOR(PromiseReaction);
 
diff --git a/Libraries/LibJS/Runtime/PromiseResolvingElementFunctions.h b/Libraries/LibJS/Runtime/PromiseResolvingElementFunctions.h
index a42e1f83ba7..ac6984f8f0c 100644
--- a/Libraries/LibJS/Runtime/PromiseResolvingElementFunctions.h
+++ b/Libraries/LibJS/Runtime/PromiseResolvingElementFunctions.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-struct RemainingElements final : public Cell {
+struct JS_API RemainingElements final : public Cell {
     GC_CELL(RemainingElements, Cell);
     GC_DECLARE_ALLOCATOR(RemainingElements);
 
@@ -27,7 +27,7 @@ private:
     }
 };
 
-class PromiseValueList final : public Cell {
+class JS_API PromiseValueList final : public Cell {
     GC_CELL(PromiseValueList, Cell);
     GC_DECLARE_ALLOCATOR(PromiseValueList);
 
@@ -43,7 +43,7 @@ private:
     Vector<Value> m_values;
 };
 
-class PromiseResolvingElementFunction : public NativeFunction {
+class JS_API PromiseResolvingElementFunction : public NativeFunction {
     JS_OBJECT(PromiseResolvingElementFunction, NativeFunction);
     GC_DECLARE_ALLOCATOR(PromiseResolvingElementFunction);
 
@@ -70,7 +70,7 @@ private:
 };
 
 // 27.2.4.1.3 Promise.all Resolve Element Functions, https://tc39.es/ecma262/#sec-promise.all-resolve-element-functions
-class PromiseAllResolveElementFunction final : public PromiseResolvingElementFunction {
+class JS_API PromiseAllResolveElementFunction final : public PromiseResolvingElementFunction {
     JS_OBJECT(PromiseAllResolveElementFunction, PromiseResolvingElementFunction);
     GC_DECLARE_ALLOCATOR(PromiseAllResolveElementFunction);
 
@@ -86,7 +86,7 @@ private:
 };
 
 // 27.2.4.2.2 Promise.allSettled Resolve Element Functions, https://tc39.es/ecma262/#sec-promise.allsettled-resolve-element-functions
-class PromiseAllSettledResolveElementFunction final : public PromiseResolvingElementFunction {
+class JS_API PromiseAllSettledResolveElementFunction final : public PromiseResolvingElementFunction {
     JS_OBJECT(PromiseAllSettledResolveElementFunction, PromiseResolvingElementFunction);
     GC_DECLARE_ALLOCATOR(PromiseAllSettledResolveElementFunction);
 
@@ -102,7 +102,7 @@ private:
 };
 
 // 27.2.4.2.3 Promise.allSettled Reject Element Functions, https://tc39.es/ecma262/#sec-promise.allsettled-reject-element-functions
-class PromiseAllSettledRejectElementFunction final : public PromiseResolvingElementFunction {
+class JS_API PromiseAllSettledRejectElementFunction final : public PromiseResolvingElementFunction {
     JS_OBJECT(PromiseAllSettledRejectElementFunction, PromiseResolvingElementFunction);
     GC_DECLARE_ALLOCATOR(PromiseAllSettledRejectElementFunction);
 
@@ -118,7 +118,7 @@ private:
 };
 
 // 27.2.4.3.2 Promise.any Reject Element Functions, https://tc39.es/ecma262/#sec-promise.any-reject-element-functions
-class PromiseAnyRejectElementFunction final : public PromiseResolvingElementFunction {
+class JS_API PromiseAnyRejectElementFunction final : public PromiseResolvingElementFunction {
     JS_OBJECT(PromiseAnyRejectElementFunction, PromiseResolvingElementFunction);
     GC_DECLARE_ALLOCATOR(PromiseAnyRejectElementFunction);
 
diff --git a/Libraries/LibJS/Runtime/PromiseResolvingFunction.h b/Libraries/LibJS/Runtime/PromiseResolvingFunction.h
index e73bf211465..662630adcf0 100644
--- a/Libraries/LibJS/Runtime/PromiseResolvingFunction.h
+++ b/Libraries/LibJS/Runtime/PromiseResolvingFunction.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-struct AlreadyResolved final : public Cell {
+struct JS_API AlreadyResolved final : public Cell {
     GC_CELL(AlreadyResolved, Cell);
     GC_DECLARE_ALLOCATOR(AlreadyResolved);
 
@@ -23,7 +23,7 @@ protected:
     u8 dummy[8];
 };
 
-class PromiseResolvingFunction final : public NativeFunction {
+class JS_API PromiseResolvingFunction final : public NativeFunction {
     JS_OBJECT(PromiseResolvingFunction, NativeFunction);
     GC_DECLARE_ALLOCATOR(PromiseResolvingFunction);
 
diff --git a/Libraries/LibJS/Runtime/PropertyAttributes.h b/Libraries/LibJS/Runtime/PropertyAttributes.h
index fa15a21ba67..791ce5ad1f0 100644
--- a/Libraries/LibJS/Runtime/PropertyAttributes.h
+++ b/Libraries/LibJS/Runtime/PropertyAttributes.h
@@ -25,7 +25,7 @@ struct Attribute {
 };
 
 // 6.1.7.1 Property Attributes, https://tc39.es/ecma262/#sec-property-attributes
-class PropertyAttributes {
+class JS_API PropertyAttributes {
 public:
     PropertyAttributes(u8 bits = 0)
         : m_bits(bits)
diff --git a/Libraries/LibJS/Runtime/PropertyDescriptor.h b/Libraries/LibJS/Runtime/PropertyDescriptor.h
index 700f8d5218e..2ada63fb480 100644
--- a/Libraries/LibJS/Runtime/PropertyDescriptor.h
+++ b/Libraries/LibJS/Runtime/PropertyDescriptor.h
@@ -18,7 +18,7 @@ namespace JS {
 Value from_property_descriptor(VM&, Optional<PropertyDescriptor> const&);
 ThrowCompletionOr<PropertyDescriptor> to_property_descriptor(VM&, Value);
 
-class PropertyDescriptor {
+class JS_API PropertyDescriptor {
 public:
     [[nodiscard]] bool is_accessor_descriptor() const;
     [[nodiscard]] bool is_data_descriptor() const;
diff --git a/Libraries/LibJS/Runtime/PropertyKey.h b/Libraries/LibJS/Runtime/PropertyKey.h
index 94ed0c3f842..cc41546d47d 100644
--- a/Libraries/LibJS/Runtime/PropertyKey.h
+++ b/Libraries/LibJS/Runtime/PropertyKey.h
@@ -14,7 +14,7 @@
 
 namespace JS {
 
-class PropertyKey {
+class JS_API PropertyKey {
 public:
     enum class StringMayBeNumber {
         Yes,
diff --git a/Libraries/LibJS/Runtime/ProxyConstructor.h b/Libraries/LibJS/Runtime/ProxyConstructor.h
index e8399d82436..da2c3431045 100644
--- a/Libraries/LibJS/Runtime/ProxyConstructor.h
+++ b/Libraries/LibJS/Runtime/ProxyConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ProxyConstructor final : public NativeFunction {
+class JS_API ProxyConstructor final : public NativeFunction {
     JS_OBJECT(ProxyConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ProxyConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ProxyObject.h b/Libraries/LibJS/Runtime/ProxyObject.h
index c499d608493..328a88976c3 100644
--- a/Libraries/LibJS/Runtime/ProxyObject.h
+++ b/Libraries/LibJS/Runtime/ProxyObject.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class ProxyObject final : public FunctionObject {
+class JS_API ProxyObject final : public FunctionObject {
     JS_OBJECT(ProxyObject, FunctionObject);
     GC_DECLARE_ALLOCATOR(ProxyObject);
 
diff --git a/Libraries/LibJS/Runtime/RawJSONObject.h b/Libraries/LibJS/Runtime/RawJSONObject.h
index f281db568b3..83abcf47dfe 100644
--- a/Libraries/LibJS/Runtime/RawJSONObject.h
+++ b/Libraries/LibJS/Runtime/RawJSONObject.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class RawJSONObject final : public Object {
+class JS_API RawJSONObject final : public Object {
     JS_OBJECT(RawJSONObject, Object);
     GC_DECLARE_ALLOCATOR(RawJSONObject);
 
diff --git a/Libraries/LibJS/Runtime/Realm.h b/Libraries/LibJS/Runtime/Realm.h
index f9c369abfec..afbdc091cdc 100644
--- a/Libraries/LibJS/Runtime/Realm.h
+++ b/Libraries/LibJS/Runtime/Realm.h
@@ -21,7 +21,7 @@
 namespace JS {
 
 // 9.3 Realms, https://tc39.es/ecma262/#realm-record
-class Realm final : public Cell {
+class JS_API Realm final : public Cell {
     GC_CELL(Realm, Cell);
     GC_DECLARE_ALLOCATOR(Realm);
 
diff --git a/Libraries/LibJS/Runtime/Reference.h b/Libraries/LibJS/Runtime/Reference.h
index 7864d4bb67d..9f4a0caf66d 100644
--- a/Libraries/LibJS/Runtime/Reference.h
+++ b/Libraries/LibJS/Runtime/Reference.h
@@ -15,7 +15,7 @@ namespace JS {
 
 Reference make_private_reference(VM&, Value base_value, FlyString const& private_identifier);
 
-class Reference {
+class JS_API Reference {
 public:
     enum class BaseType : u8 {
         Unresolvable,
diff --git a/Libraries/LibJS/Runtime/ReflectObject.h b/Libraries/LibJS/Runtime/ReflectObject.h
index f99464843e7..6f915ee2328 100644
--- a/Libraries/LibJS/Runtime/ReflectObject.h
+++ b/Libraries/LibJS/Runtime/ReflectObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ReflectObject final : public Object {
+class JS_API ReflectObject final : public Object {
     JS_OBJECT(ReflectObject, Object);
     GC_DECLARE_ALLOCATOR(ReflectObject);
 
diff --git a/Libraries/LibJS/Runtime/RegExpConstructor.h b/Libraries/LibJS/Runtime/RegExpConstructor.h
index eab56c324d7..e492f6439b2 100644
--- a/Libraries/LibJS/Runtime/RegExpConstructor.h
+++ b/Libraries/LibJS/Runtime/RegExpConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class RegExpConstructor final : public NativeFunction {
+class JS_API RegExpConstructor final : public NativeFunction {
     JS_OBJECT(RegExpConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(RegExpConstructor);
 
diff --git a/Libraries/LibJS/Runtime/RegExpLegacyStaticProperties.h b/Libraries/LibJS/Runtime/RegExpLegacyStaticProperties.h
index f861ad6c879..eebce857598 100644
--- a/Libraries/LibJS/Runtime/RegExpLegacyStaticProperties.h
+++ b/Libraries/LibJS/Runtime/RegExpLegacyStaticProperties.h
@@ -20,7 +20,7 @@ namespace JS {
 // [[RegExpLeftContext]]
 // [[RegExpRightContext]]
 // [[RegExpParen1]] ... [[RegExpParen9]]
-class RegExpLegacyStaticProperties {
+class JS_API RegExpLegacyStaticProperties {
 public:
     Optional<Utf16String> const& input() const { return m_input; }
     Optional<Utf16String> const& last_match() const
@@ -102,9 +102,9 @@ private:
     mutable Optional<Utf16String> m_right_context_string;
 };
 
-ThrowCompletionOr<void> set_legacy_regexp_static_property(VM& vm, RegExpConstructor& constructor, Value this_value, void (RegExpLegacyStaticProperties::*property_setter)(Utf16String), Value value);
-ThrowCompletionOr<Value> get_legacy_regexp_static_property(VM& vm, RegExpConstructor& constructor, Value this_value, Optional<Utf16String> const& (RegExpLegacyStaticProperties::*property_getter)() const);
-void update_legacy_regexp_static_properties(RegExpConstructor& constructor, Utf16String const& string, size_t start_index, size_t end_index, Vector<Utf16String> const& captured_values);
-void invalidate_legacy_regexp_static_properties(RegExpConstructor& constructor);
+JS_API ThrowCompletionOr<void> set_legacy_regexp_static_property(VM& vm, RegExpConstructor& constructor, Value this_value, void (RegExpLegacyStaticProperties::*property_setter)(Utf16String), Value value);
+JS_API ThrowCompletionOr<Value> get_legacy_regexp_static_property(VM& vm, RegExpConstructor& constructor, Value this_value, Optional<Utf16String> const& (RegExpLegacyStaticProperties::*property_getter)() const);
+JS_API void update_legacy_regexp_static_properties(RegExpConstructor& constructor, Utf16String const& string, size_t start_index, size_t end_index, Vector<Utf16String> const& captured_values);
+JS_API void invalidate_legacy_regexp_static_properties(RegExpConstructor& constructor);
 
 }
diff --git a/Libraries/LibJS/Runtime/RegExpObject.h b/Libraries/LibJS/Runtime/RegExpObject.h
index 397a0d53b22..c33d071442a 100644
--- a/Libraries/LibJS/Runtime/RegExpObject.h
+++ b/Libraries/LibJS/Runtime/RegExpObject.h
@@ -15,17 +15,17 @@
 
 namespace JS {
 
-ThrowCompletionOr<GC::Ref<RegExpObject>> regexp_create(VM&, Value pattern, Value flags);
-ThrowCompletionOr<GC::Ref<RegExpObject>> regexp_alloc(VM&, FunctionObject& new_target);
+JS_API ThrowCompletionOr<GC::Ref<RegExpObject>> regexp_create(VM&, Value pattern, Value flags);
+JS_API ThrowCompletionOr<GC::Ref<RegExpObject>> regexp_alloc(VM&, FunctionObject& new_target);
 
-Result<regex::RegexOptions<ECMAScriptFlags>, String> regex_flags_from_string(StringView flags);
+JS_API Result<regex::RegexOptions<ECMAScriptFlags>, String> regex_flags_from_string(StringView flags);
 struct ParseRegexPatternError {
     String error;
 };
-ErrorOr<String, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets);
-ThrowCompletionOr<String> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets);
+JS_API ErrorOr<String, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets);
+JS_API ThrowCompletionOr<String> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets);
 
-class RegExpObject : public Object {
+class JS_API RegExpObject : public Object {
     JS_OBJECT(RegExpObject, Object);
     GC_DECLARE_ALLOCATOR(RegExpObject);
 
diff --git a/Libraries/LibJS/Runtime/RegExpPrototype.h b/Libraries/LibJS/Runtime/RegExpPrototype.h
index 6817f6fc170..aa1c43f3128 100644
--- a/Libraries/LibJS/Runtime/RegExpPrototype.h
+++ b/Libraries/LibJS/Runtime/RegExpPrototype.h
@@ -12,10 +12,10 @@
 
 namespace JS {
 
-ThrowCompletionOr<Value> regexp_exec(VM&, Object& regexp_object, GC::Ref<PrimitiveString> string);
-size_t advance_string_index(Utf16View const& string, size_t index, bool unicode);
+JS_API ThrowCompletionOr<Value> regexp_exec(VM&, Object& regexp_object, GC::Ref<PrimitiveString> string);
+JS_API size_t advance_string_index(Utf16View const& string, size_t index, bool unicode);
 
-class RegExpPrototype final : public PrototypeObject<RegExpPrototype, RegExpObject> {
+class JS_API RegExpPrototype final : public PrototypeObject<RegExpPrototype, RegExpObject> {
     JS_PROTOTYPE_OBJECT(RegExpPrototype, RegExpObject, RegExp);
     GC_DECLARE_ALLOCATOR(RegExpPrototype);
 
diff --git a/Libraries/LibJS/Runtime/RegExpStringIterator.h b/Libraries/LibJS/Runtime/RegExpStringIterator.h
index 8bc6b7c78e3..1904abd2d24 100644
--- a/Libraries/LibJS/Runtime/RegExpStringIterator.h
+++ b/Libraries/LibJS/Runtime/RegExpStringIterator.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class RegExpStringIterator final : public Object {
+class JS_API RegExpStringIterator final : public Object {
     JS_OBJECT(RegExpStringIterator, Object);
     GC_DECLARE_ALLOCATOR(RegExpStringIterator);
 
diff --git a/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.h b/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.h
index 9355c3e3901..1d43aaf8d3c 100644
--- a/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class RegExpStringIteratorPrototype final : public PrototypeObject<RegExpStringIteratorPrototype, RegExpStringIterator> {
+class JS_API RegExpStringIteratorPrototype final : public PrototypeObject<RegExpStringIteratorPrototype, RegExpStringIterator> {
     JS_PROTOTYPE_OBJECT(RegExpStringIteratorPrototype, RegExpStringIterator, RegExpStringIterator);
     GC_DECLARE_ALLOCATOR(RegExpStringIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Set.h b/Libraries/LibJS/Runtime/Set.h
index 3c369ed7961..8a94751eeef 100644
--- a/Libraries/LibJS/Runtime/Set.h
+++ b/Libraries/LibJS/Runtime/Set.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class Set : public Object {
+class JS_API Set : public Object {
     JS_OBJECT(Set, Object);
     GC_DECLARE_ALLOCATOR(Set);
 
@@ -55,7 +55,7 @@ struct SetRecord {
     GC::Ref<FunctionObject> keys;     // [[Keys]]
 };
 
-ThrowCompletionOr<SetRecord> get_set_record(VM&, Value);
-bool set_data_has(GC::Ref<Set>, Value);
+JS_API ThrowCompletionOr<SetRecord> get_set_record(VM&, Value);
+JS_API bool set_data_has(GC::Ref<Set>, Value);
 
 }
diff --git a/Libraries/LibJS/Runtime/SetConstructor.h b/Libraries/LibJS/Runtime/SetConstructor.h
index 2ebbe63879b..d0cf8c12b29 100644
--- a/Libraries/LibJS/Runtime/SetConstructor.h
+++ b/Libraries/LibJS/Runtime/SetConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SetConstructor final : public NativeFunction {
+class JS_API SetConstructor final : public NativeFunction {
     JS_OBJECT(SetConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(SetConstructor);
 
diff --git a/Libraries/LibJS/Runtime/SetIterator.h b/Libraries/LibJS/Runtime/SetIterator.h
index d22019523ce..d4ba5fa4b36 100644
--- a/Libraries/LibJS/Runtime/SetIterator.h
+++ b/Libraries/LibJS/Runtime/SetIterator.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class SetIterator final : public Object
+class JS_API SetIterator final : public Object
     , public BuiltinIterator {
     JS_OBJECT(SetIterator, Object);
     GC_DECLARE_ALLOCATOR(SetIterator);
diff --git a/Libraries/LibJS/Runtime/SetIteratorPrototype.h b/Libraries/LibJS/Runtime/SetIteratorPrototype.h
index 816d8a3f4a1..d388c79d04e 100644
--- a/Libraries/LibJS/Runtime/SetIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/SetIteratorPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class SetIteratorPrototype final : public PrototypeObject<SetIteratorPrototype, SetIterator> {
+class JS_API SetIteratorPrototype final : public PrototypeObject<SetIteratorPrototype, SetIterator> {
     JS_PROTOTYPE_OBJECT(SetIteratorPrototype, SetIterator, SetIterator);
     GC_DECLARE_ALLOCATOR(SetIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/SetPrototype.h b/Libraries/LibJS/Runtime/SetPrototype.h
index 1ef332ca67b..9bdc63a375e 100644
--- a/Libraries/LibJS/Runtime/SetPrototype.h
+++ b/Libraries/LibJS/Runtime/SetPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class SetPrototype final : public PrototypeObject<SetPrototype, Set> {
+class JS_API SetPrototype final : public PrototypeObject<SetPrototype, Set> {
     JS_PROTOTYPE_OBJECT(SetPrototype, Set, Set);
     GC_DECLARE_ALLOCATOR(SetPrototype);
 
diff --git a/Libraries/LibJS/Runtime/ShadowRealm.h b/Libraries/LibJS/Runtime/ShadowRealm.h
index 6c178094dd8..17fe6e31b74 100644
--- a/Libraries/LibJS/Runtime/ShadowRealm.h
+++ b/Libraries/LibJS/Runtime/ShadowRealm.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class ShadowRealm final : public Object {
+class JS_API ShadowRealm final : public Object {
     JS_OBJECT(ShadowRealm, Object);
     GC_DECLARE_ALLOCATOR(ShadowRealm);
 
diff --git a/Libraries/LibJS/Runtime/ShadowRealmConstructor.h b/Libraries/LibJS/Runtime/ShadowRealmConstructor.h
index 080d38cc0ab..67f63b9ad96 100644
--- a/Libraries/LibJS/Runtime/ShadowRealmConstructor.h
+++ b/Libraries/LibJS/Runtime/ShadowRealmConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class ShadowRealmConstructor final : public NativeFunction {
+class JS_API ShadowRealmConstructor final : public NativeFunction {
     JS_OBJECT(ShadowRealmConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ShadowRealmConstructor);
 
diff --git a/Libraries/LibJS/Runtime/ShadowRealmPrototype.h b/Libraries/LibJS/Runtime/ShadowRealmPrototype.h
index 3c2ffa7ee6a..37bc2c28109 100644
--- a/Libraries/LibJS/Runtime/ShadowRealmPrototype.h
+++ b/Libraries/LibJS/Runtime/ShadowRealmPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class ShadowRealmPrototype final : public PrototypeObject<ShadowRealmPrototype, ShadowRealm> {
+class JS_API ShadowRealmPrototype final : public PrototypeObject<ShadowRealmPrototype, ShadowRealm> {
     JS_PROTOTYPE_OBJECT(ShadowRealmPrototype, ShadowRealm, ShadowRealm);
     GC_DECLARE_ALLOCATOR(ShadowRealmPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Shape.h b/Libraries/LibJS/Runtime/Shape.h
index c8fc44b8795..bdfff9b4ed2 100644
--- a/Libraries/LibJS/Runtime/Shape.h
+++ b/Libraries/LibJS/Runtime/Shape.h
@@ -34,7 +34,7 @@ struct TransitionKey {
     }
 };
 
-class PrototypeChainValidity final : public Cell
+class JS_API PrototypeChainValidity final : public Cell
     , public Weakable<PrototypeChainValidity> {
     GC_CELL(PrototypeChainValidity, Cell);
     GC_DECLARE_ALLOCATOR(PrototypeChainValidity);
@@ -48,7 +48,7 @@ private:
     size_t padding { 0 };
 };
 
-class Shape final : public Cell
+class JS_API Shape final : public Cell
     , public Weakable<Shape> {
     GC_CELL(Shape, Cell);
     GC_DECLARE_ALLOCATOR(Shape);
diff --git a/Libraries/LibJS/Runtime/SharedArrayBufferConstructor.h b/Libraries/LibJS/Runtime/SharedArrayBufferConstructor.h
index ef4016ed197..6cad1f7a929 100644
--- a/Libraries/LibJS/Runtime/SharedArrayBufferConstructor.h
+++ b/Libraries/LibJS/Runtime/SharedArrayBufferConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SharedArrayBufferConstructor final : public NativeFunction {
+class JS_API SharedArrayBufferConstructor final : public NativeFunction {
     JS_OBJECT(SharedArrayBufferConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(SharedArrayBufferConstructor);
 
diff --git a/Libraries/LibJS/Runtime/SharedArrayBufferPrototype.h b/Libraries/LibJS/Runtime/SharedArrayBufferPrototype.h
index dc96ae2218a..2a063eed06a 100644
--- a/Libraries/LibJS/Runtime/SharedArrayBufferPrototype.h
+++ b/Libraries/LibJS/Runtime/SharedArrayBufferPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class SharedArrayBufferPrototype final : public PrototypeObject<SharedArrayBufferPrototype, ArrayBuffer> {
+class JS_API SharedArrayBufferPrototype final : public PrototypeObject<SharedArrayBufferPrototype, ArrayBuffer> {
     JS_PROTOTYPE_OBJECT(SharedArrayBufferPrototype, ArrayBuffer, SharedArrayBuffer);
     GC_DECLARE_ALLOCATOR(SharedArrayBufferPrototype);
 
diff --git a/Libraries/LibJS/Runtime/StringConstructor.h b/Libraries/LibJS/Runtime/StringConstructor.h
index 785c2d714b6..7c96a24d80f 100644
--- a/Libraries/LibJS/Runtime/StringConstructor.h
+++ b/Libraries/LibJS/Runtime/StringConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class StringConstructor final : public NativeFunction {
+class JS_API StringConstructor final : public NativeFunction {
     JS_OBJECT(StringConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(StringConstructor);
 
diff --git a/Libraries/LibJS/Runtime/StringIterator.h b/Libraries/LibJS/Runtime/StringIterator.h
index 858452aace0..cb2ccb7db19 100644
--- a/Libraries/LibJS/Runtime/StringIterator.h
+++ b/Libraries/LibJS/Runtime/StringIterator.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class StringIterator final : public Object
+class JS_API StringIterator final : public Object
     , public BuiltinIterator {
     JS_OBJECT(StringIterator, Object);
     GC_DECLARE_ALLOCATOR(StringIterator);
diff --git a/Libraries/LibJS/Runtime/StringIteratorPrototype.h b/Libraries/LibJS/Runtime/StringIteratorPrototype.h
index eb852fb4f79..a1a494bf851 100644
--- a/Libraries/LibJS/Runtime/StringIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/StringIteratorPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class StringIteratorPrototype final : public PrototypeObject<StringIteratorPrototype, StringIterator> {
+class JS_API StringIteratorPrototype final : public PrototypeObject<StringIteratorPrototype, StringIterator> {
     JS_PROTOTYPE_OBJECT(StringIteratorPrototype, StringIterator, StringIterator);
     GC_DECLARE_ALLOCATOR(StringIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/StringObject.h b/Libraries/LibJS/Runtime/StringObject.h
index 9d95a91e17f..63dba0c902d 100644
--- a/Libraries/LibJS/Runtime/StringObject.h
+++ b/Libraries/LibJS/Runtime/StringObject.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class StringObject : public Object {
+class JS_API StringObject : public Object {
     JS_OBJECT(StringObject, Object);
     GC_DECLARE_ALLOCATOR(StringObject);
 
diff --git a/Libraries/LibJS/Runtime/StringPrototype.h b/Libraries/LibJS/Runtime/StringPrototype.h
index b8f1375eacc..b6c49793e3a 100644
--- a/Libraries/LibJS/Runtime/StringPrototype.h
+++ b/Libraries/LibJS/Runtime/StringPrototype.h
@@ -17,13 +17,13 @@ struct CodePoint {
     size_t code_unit_count { 0 };
 };
 
-Optional<size_t> string_index_of(Utf16View const& string, Utf16View const& search_value, size_t from_index);
-CodePoint code_point_at(Utf16View const& string, size_t position);
-String to_well_formed_string(Utf16String const&);
+JS_API Optional<size_t> string_index_of(Utf16View const& string, Utf16View const& search_value, size_t from_index);
+JS_API CodePoint code_point_at(Utf16View const& string, size_t position);
+JS_API String to_well_formed_string(Utf16String const&);
 static constexpr Utf8View whitespace_characters = Utf8View("\x09\x0A\x0B\x0C\x0D\x20\xC2\xA0\xE1\x9A\x80\xE2\x80\x80\xE2\x80\x81\xE2\x80\x82\xE2\x80\x83\xE2\x80\x84\xE2\x80\x85\xE2\x80\x86\xE2\x80\x87\xE2\x80\x88\xE2\x80\x89\xE2\x80\x8A\xE2\x80\xAF\xE2\x81\x9F\xE3\x80\x80\xE2\x80\xA8\xE2\x80\xA9\xEF\xBB\xBF"sv);
-ThrowCompletionOr<String> trim_string(VM&, Value string, TrimMode where);
+JS_API ThrowCompletionOr<String> trim_string(VM&, Value string, TrimMode where);
 
-class StringPrototype final : public StringObject {
+class JS_API StringPrototype final : public StringObject {
     JS_OBJECT(StringPrototype, StringObject);
     GC_DECLARE_ALLOCATOR(StringPrototype);
 
diff --git a/Libraries/LibJS/Runtime/SuppressedError.h b/Libraries/LibJS/Runtime/SuppressedError.h
index 6061d8468b7..424cd3f4fc2 100644
--- a/Libraries/LibJS/Runtime/SuppressedError.h
+++ b/Libraries/LibJS/Runtime/SuppressedError.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SuppressedError : public Error {
+class JS_API SuppressedError : public Error {
     JS_OBJECT(SuppressedError, Error);
     GC_DECLARE_ALLOCATOR(SuppressedError);
 
diff --git a/Libraries/LibJS/Runtime/SuppressedErrorConstructor.h b/Libraries/LibJS/Runtime/SuppressedErrorConstructor.h
index 276efb6f6a6..7f2c0a16c96 100644
--- a/Libraries/LibJS/Runtime/SuppressedErrorConstructor.h
+++ b/Libraries/LibJS/Runtime/SuppressedErrorConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SuppressedErrorConstructor final : public NativeFunction {
+class JS_API SuppressedErrorConstructor final : public NativeFunction {
     JS_OBJECT(SuppressedErrorConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(SuppressedErrorConstructor);
 
diff --git a/Libraries/LibJS/Runtime/SuppressedErrorPrototype.h b/Libraries/LibJS/Runtime/SuppressedErrorPrototype.h
index 6a55ac43262..d9b63c13c36 100644
--- a/Libraries/LibJS/Runtime/SuppressedErrorPrototype.h
+++ b/Libraries/LibJS/Runtime/SuppressedErrorPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SuppressedErrorPrototype final : public Object {
+class JS_API SuppressedErrorPrototype final : public Object {
     JS_OBJECT(SuppressedErrorPrototype, Object);
     GC_DECLARE_ALLOCATOR(SuppressedErrorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Symbol.h b/Libraries/LibJS/Runtime/Symbol.h
index 02b66a7d1df..35625ed44ad 100644
--- a/Libraries/LibJS/Runtime/Symbol.h
+++ b/Libraries/LibJS/Runtime/Symbol.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class Symbol final : public Cell {
+class JS_API Symbol final : public Cell {
     GC_CELL(Symbol, Cell);
     GC_DECLARE_ALLOCATOR(Symbol);
 
diff --git a/Libraries/LibJS/Runtime/SymbolConstructor.h b/Libraries/LibJS/Runtime/SymbolConstructor.h
index 7ef26894e7f..5ea831df800 100644
--- a/Libraries/LibJS/Runtime/SymbolConstructor.h
+++ b/Libraries/LibJS/Runtime/SymbolConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SymbolConstructor final : public NativeFunction {
+class JS_API SymbolConstructor final : public NativeFunction {
     JS_OBJECT(SymbolConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(SymbolConstructor);
 
diff --git a/Libraries/LibJS/Runtime/SymbolObject.h b/Libraries/LibJS/Runtime/SymbolObject.h
index 78514af39a3..7e6c611d89b 100644
--- a/Libraries/LibJS/Runtime/SymbolObject.h
+++ b/Libraries/LibJS/Runtime/SymbolObject.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class SymbolObject : public Object {
+class JS_API SymbolObject : public Object {
     JS_OBJECT(SymbolObject, Object);
     GC_DECLARE_ALLOCATOR(SymbolObject);
 
diff --git a/Libraries/LibJS/Runtime/SymbolPrototype.h b/Libraries/LibJS/Runtime/SymbolPrototype.h
index 0f097aaf104..7905dcd74af 100644
--- a/Libraries/LibJS/Runtime/SymbolPrototype.h
+++ b/Libraries/LibJS/Runtime/SymbolPrototype.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class SymbolPrototype final : public Object {
+class JS_API SymbolPrototype final : public Object {
     JS_OBJECT(SymbolPrototype, Object);
     GC_DECLARE_ALLOCATOR(SymbolPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h b/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
index ae3d038490b..8adbf48f7d4 100644
--- a/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
+++ b/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
@@ -99,7 +99,7 @@ enum class Unit {
     Microsecond,
     Nanosecond,
 };
-StringView temporal_unit_to_string(Unit);
+JS_API StringView temporal_unit_to_string(Unit);
 
 // https://tc39.es/proposal-temporal/#sec-temporal-units
 enum class UnitCategory {
@@ -157,44 +157,44 @@ struct DifferenceSettings {
     u64 rounding_increment { 0 };
 };
 
-double iso_date_to_epoch_days(double year, double month, double date);
-double epoch_days_to_epoch_ms(double day, double time);
-ThrowCompletionOr<void> check_iso_days_range(VM&, ISODate);
-ThrowCompletionOr<Overflow> get_temporal_overflow_option(VM&, Object const& options);
-ThrowCompletionOr<Disambiguation> get_temporal_disambiguation_option(VM&, Object const& options);
-RoundingMode negate_rounding_mode(RoundingMode);
-ThrowCompletionOr<OffsetOption> get_temporal_offset_option(VM&, Object const& options, OffsetOption fallback);
-ThrowCompletionOr<ShowTimeZoneName> get_temporal_show_time_zone_name_option(VM&, Object const& options);
-ThrowCompletionOr<ShowOffset> get_temporal_show_offset_option(VM&, Object const& options);
-ThrowCompletionOr<ShowCalendar> get_temporal_show_calendar_name_option(VM&, Object const& options);
-ThrowCompletionOr<Direction> get_direction_option(VM&, Object const& options);
-ThrowCompletionOr<void> validate_temporal_rounding_increment(VM&, u64 increment, u64 dividend, bool inclusive);
-ThrowCompletionOr<Precision> get_temporal_fractional_second_digits_option(VM&, Object const& options);
-SecondsStringPrecision to_seconds_string_precision_record(UnitValue, Precision);
-ThrowCompletionOr<UnitValue> get_temporal_unit_valued_option(VM&, Object const& options, PropertyKey const&, UnitGroup, UnitDefault const&, ReadonlySpan<UnitValue> extra_values = {});
-ThrowCompletionOr<RelativeTo> get_temporal_relative_to_option(VM&, Object const& options);
-Unit larger_of_two_temporal_units(Unit, Unit);
-bool is_calendar_unit(Unit);
-UnitCategory temporal_unit_category(Unit);
-RoundingIncrement maximum_temporal_duration_rounding_increment(Unit);
-Crypto::UnsignedBigInteger const& temporal_unit_length_in_nanoseconds(Unit);
-ThrowCompletionOr<bool> is_partial_temporal_object(VM&, Value);
-String format_fractional_seconds(u64, Precision);
-String format_time_string(u8 hour, u8 minute, u8 second, u64 sub_second_nanoseconds, SecondsStringPrecision::Precision, Optional<TimeStyle> = {});
-UnsignedRoundingMode get_unsigned_rounding_mode(RoundingMode, Sign);
-double apply_unsigned_rounding_mode(double, double r1, double r2, UnsignedRoundingMode);
-Crypto::SignedBigInteger apply_unsigned_rounding_mode(Crypto::SignedDivisionResult const&, Crypto::SignedBigInteger r1, Crypto::SignedBigInteger r2, UnsignedRoundingMode, Crypto::UnsignedBigInteger const& increment);
-double round_number_to_increment(double, u64 increment, RoundingMode);
-Crypto::SignedBigInteger round_number_to_increment(Crypto::SignedBigInteger const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
-Crypto::SignedBigInteger round_number_to_increment_as_if_positive(Crypto::SignedBigInteger const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
-ThrowCompletionOr<ParsedISODateTime> parse_iso_date_time(VM&, StringView iso_string, ReadonlySpan<Production> allowed_formats);
-ThrowCompletionOr<String> parse_temporal_calendar_string(VM&, String const&);
-ThrowCompletionOr<GC::Ref<Duration>> parse_temporal_duration_string(VM&, StringView iso_string);
-ThrowCompletionOr<TimeZone> parse_temporal_time_zone_string(VM&, StringView time_zone_string);
-ThrowCompletionOr<String> to_month_code(VM&, Value argument);
-ThrowCompletionOr<String> to_offset_string(VM&, Value argument);
-CalendarFields iso_date_to_fields(StringView calendar, ISODate, DateType);
-ThrowCompletionOr<DifferenceSettings> get_difference_settings(VM&, DurationOperation, Object const& options, UnitGroup, ReadonlySpan<Unit> disallowed_units, Unit fallback_smallest_unit, Unit smallest_largest_default_unit);
+JS_API double iso_date_to_epoch_days(double year, double month, double date);
+JS_API double epoch_days_to_epoch_ms(double day, double time);
+JS_API ThrowCompletionOr<void> check_iso_days_range(VM&, ISODate);
+JS_API ThrowCompletionOr<Overflow> get_temporal_overflow_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<Disambiguation> get_temporal_disambiguation_option(VM&, Object const& options);
+JS_API RoundingMode negate_rounding_mode(RoundingMode);
+JS_API ThrowCompletionOr<OffsetOption> get_temporal_offset_option(VM&, Object const& options, OffsetOption fallback);
+JS_API ThrowCompletionOr<ShowTimeZoneName> get_temporal_show_time_zone_name_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<ShowOffset> get_temporal_show_offset_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<ShowCalendar> get_temporal_show_calendar_name_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<Direction> get_direction_option(VM&, Object const& options);
+JS_API ThrowCompletionOr<void> validate_temporal_rounding_increment(VM&, u64 increment, u64 dividend, bool inclusive);
+JS_API ThrowCompletionOr<Precision> get_temporal_fractional_second_digits_option(VM&, Object const& options);
+JS_API SecondsStringPrecision to_seconds_string_precision_record(UnitValue, Precision);
+JS_API ThrowCompletionOr<UnitValue> get_temporal_unit_valued_option(VM&, Object const& options, PropertyKey const&, UnitGroup, UnitDefault const&, ReadonlySpan<UnitValue> extra_values = {});
+JS_API ThrowCompletionOr<RelativeTo> get_temporal_relative_to_option(VM&, Object const& options);
+JS_API Unit larger_of_two_temporal_units(Unit, Unit);
+JS_API bool is_calendar_unit(Unit);
+JS_API UnitCategory temporal_unit_category(Unit);
+JS_API RoundingIncrement maximum_temporal_duration_rounding_increment(Unit);
+JS_API Crypto::UnsignedBigInteger const& temporal_unit_length_in_nanoseconds(Unit);
+JS_API ThrowCompletionOr<bool> is_partial_temporal_object(VM&, Value);
+JS_API String format_fractional_seconds(u64, Precision);
+JS_API String format_time_string(u8 hour, u8 minute, u8 second, u64 sub_second_nanoseconds, SecondsStringPrecision::Precision, Optional<TimeStyle> = {});
+JS_API UnsignedRoundingMode get_unsigned_rounding_mode(RoundingMode, Sign);
+JS_API double apply_unsigned_rounding_mode(double, double r1, double r2, UnsignedRoundingMode);
+JS_API Crypto::SignedBigInteger apply_unsigned_rounding_mode(Crypto::SignedDivisionResult const&, Crypto::SignedBigInteger r1, Crypto::SignedBigInteger r2, UnsignedRoundingMode, Crypto::UnsignedBigInteger const& increment);
+JS_API double round_number_to_increment(double, u64 increment, RoundingMode);
+JS_API Crypto::SignedBigInteger round_number_to_increment(Crypto::SignedBigInteger const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
+JS_API Crypto::SignedBigInteger round_number_to_increment_as_if_positive(Crypto::SignedBigInteger const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
+JS_API ThrowCompletionOr<ParsedISODateTime> parse_iso_date_time(VM&, StringView iso_string, ReadonlySpan<Production> allowed_formats);
+JS_API ThrowCompletionOr<String> parse_temporal_calendar_string(VM&, String const&);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> parse_temporal_duration_string(VM&, StringView iso_string);
+JS_API ThrowCompletionOr<TimeZone> parse_temporal_time_zone_string(VM&, StringView time_zone_string);
+JS_API ThrowCompletionOr<String> to_month_code(VM&, Value argument);
+JS_API ThrowCompletionOr<String> to_offset_string(VM&, Value argument);
+JS_API CalendarFields iso_date_to_fields(StringView calendar, ISODate, DateType);
+JS_API ThrowCompletionOr<DifferenceSettings> get_difference_settings(VM&, DurationOperation, Object const& options, UnitGroup, ReadonlySpan<Unit> disallowed_units, Unit fallback_smallest_unit, Unit smallest_largest_default_unit);
 
 // 13.38 ToIntegerWithTruncation ( argument ), https://tc39.es/proposal-temporal/#sec-tointegerwithtruncation
 template<typename... Args>
diff --git a/Libraries/LibJS/Runtime/Temporal/Calendar.h b/Libraries/LibJS/Runtime/Temporal/Calendar.h
index 26ac2399a31..21ab88f8e04 100644
--- a/Libraries/LibJS/Runtime/Temporal/Calendar.h
+++ b/Libraries/LibJS/Runtime/Temporal/Calendar.h
@@ -96,29 +96,29 @@ struct Partial { };
 using CalendarFieldList = ReadonlySpan<CalendarField>;
 using CalendarFieldListOrPartial = Variant<Partial, CalendarFieldList>;
 
-ThrowCompletionOr<String> canonicalize_calendar(VM&, StringView id);
-Vector<String> const& available_calendars();
-ThrowCompletionOr<CalendarFields> prepare_calendar_fields(VM&, StringView calendar, Object const& fields, CalendarFieldList calendar_field_names, CalendarFieldList non_calendar_field_names, CalendarFieldListOrPartial required_field_names);
-ThrowCompletionOr<ISODate> calendar_date_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
-ThrowCompletionOr<ISODate> calendar_year_month_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
-ThrowCompletionOr<ISODate> calendar_month_day_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
-String format_calendar_annotation(StringView id, ShowCalendar);
-bool calendar_equals(StringView one, StringView two);
-u8 iso_days_in_month(double year, double month);
-YearWeek iso_week_of_year(ISODate);
-u16 iso_day_of_year(ISODate);
-u8 iso_day_of_week(ISODate);
-Vector<CalendarField> calendar_field_keys_present(CalendarFields const&);
-CalendarFields calendar_merge_fields(StringView calendar, CalendarFields const& fields, CalendarFields const& additional_fields);
-ThrowCompletionOr<ISODate> calendar_date_add(VM&, StringView calendar, ISODate, DateDuration const&, Overflow);
-DateDuration calendar_date_until(VM&, StringView calendar, ISODate, ISODate, Unit largest_unit);
-ThrowCompletionOr<String> to_temporal_calendar_identifier(VM&, Value temporal_calendar_like);
-ThrowCompletionOr<String> get_temporal_calendar_identifier_with_iso_default(VM&, Object const& item);
-ThrowCompletionOr<ISODate> calendar_date_to_iso(VM&, StringView calendar, CalendarFields const&, Overflow);
-ThrowCompletionOr<ISODate> calendar_month_day_to_iso_reference_date(VM&, StringView calendar, CalendarFields const&, Overflow);
-CalendarDate calendar_iso_to_date(StringView calendar, ISODate);
-Vector<CalendarField> calendar_extra_fields(StringView calendar, CalendarFieldList);
-Vector<CalendarField> calendar_field_keys_to_ignore(StringView calendar, ReadonlySpan<CalendarField>);
-ThrowCompletionOr<void> calendar_resolve_fields(VM&, StringView calendar, CalendarFields&, DateType);
+JS_API ThrowCompletionOr<String> canonicalize_calendar(VM&, StringView id);
+JS_API Vector<String> const& available_calendars();
+JS_API ThrowCompletionOr<CalendarFields> prepare_calendar_fields(VM&, StringView calendar, Object const& fields, CalendarFieldList calendar_field_names, CalendarFieldList non_calendar_field_names, CalendarFieldListOrPartial required_field_names);
+JS_API ThrowCompletionOr<ISODate> calendar_date_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
+JS_API ThrowCompletionOr<ISODate> calendar_year_month_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
+JS_API ThrowCompletionOr<ISODate> calendar_month_day_from_fields(VM&, StringView calendar, CalendarFields&, Overflow);
+JS_API String format_calendar_annotation(StringView id, ShowCalendar);
+JS_API bool calendar_equals(StringView one, StringView two);
+JS_API u8 iso_days_in_month(double year, double month);
+JS_API YearWeek iso_week_of_year(ISODate);
+JS_API u16 iso_day_of_year(ISODate);
+JS_API u8 iso_day_of_week(ISODate);
+JS_API Vector<CalendarField> calendar_field_keys_present(CalendarFields const&);
+JS_API CalendarFields calendar_merge_fields(StringView calendar, CalendarFields const& fields, CalendarFields const& additional_fields);
+JS_API ThrowCompletionOr<ISODate> calendar_date_add(VM&, StringView calendar, ISODate, DateDuration const&, Overflow);
+JS_API DateDuration calendar_date_until(VM&, StringView calendar, ISODate, ISODate, Unit largest_unit);
+JS_API ThrowCompletionOr<String> to_temporal_calendar_identifier(VM&, Value temporal_calendar_like);
+JS_API ThrowCompletionOr<String> get_temporal_calendar_identifier_with_iso_default(VM&, Object const& item);
+JS_API ThrowCompletionOr<ISODate> calendar_date_to_iso(VM&, StringView calendar, CalendarFields const&, Overflow);
+JS_API ThrowCompletionOr<ISODate> calendar_month_day_to_iso_reference_date(VM&, StringView calendar, CalendarFields const&, Overflow);
+JS_API CalendarDate calendar_iso_to_date(StringView calendar, ISODate);
+JS_API Vector<CalendarField> calendar_extra_fields(StringView calendar, CalendarFieldList);
+JS_API Vector<CalendarField> calendar_field_keys_to_ignore(StringView calendar, ReadonlySpan<CalendarField>);
+JS_API ThrowCompletionOr<void> calendar_resolve_fields(VM&, StringView calendar, CalendarFields&, DateType);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/DateEquations.h b/Libraries/LibJS/Runtime/Temporal/DateEquations.h
index 659691830fd..66be1aeef30 100644
--- a/Libraries/LibJS/Runtime/Temporal/DateEquations.h
+++ b/Libraries/LibJS/Runtime/Temporal/DateEquations.h
@@ -7,20 +7,21 @@
 #pragma once
 
 #include <AK/Types.h>
+#include <LibJS/Forward.h>
 
 namespace JS::Temporal {
 
 // 13.3 Date Equations, https://tc39.es/proposal-temporal/#sec-date-equations
 
-u16 mathematical_days_in_year(i32 year);
-u8 mathematical_in_leap_year(double time);
-double epoch_time_to_day_number(double time);
-double epoch_day_number_for_year(double year);
-double epoch_time_for_year(double year);
-i32 epoch_time_to_epoch_year(double time);
-u16 epoch_time_to_day_in_year(double time);
-u8 epoch_time_to_month_in_year(double time);
-u8 epoch_time_to_week_day(double time);
-u8 epoch_time_to_date(double time);
+JS_API u16 mathematical_days_in_year(i32 year);
+JS_API u8 mathematical_in_leap_year(double time);
+JS_API double epoch_time_to_day_number(double time);
+JS_API double epoch_day_number_for_year(double year);
+JS_API double epoch_time_for_year(double year);
+JS_API i32 epoch_time_to_epoch_year(double time);
+JS_API u16 epoch_time_to_day_in_year(double time);
+JS_API u8 epoch_time_to_month_in_year(double time);
+JS_API u8 epoch_time_to_week_day(double time);
+JS_API u8 epoch_time_to_date(double time);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/Duration.h b/Libraries/LibJS/Runtime/Temporal/Duration.h
index ecb13603a34..6fe69720a2a 100644
--- a/Libraries/LibJS/Runtime/Temporal/Duration.h
+++ b/Libraries/LibJS/Runtime/Temporal/Duration.h
@@ -30,7 +30,7 @@ namespace JS::Temporal {
     __JS_ENUMERATE(microseconds)    \
     __JS_ENUMERATE(nanoseconds)
 
-class Duration final : public Object {
+class JS_API Duration final : public Object {
     JS_OBJECT(Duration, Object);
     GC_DECLARE_ALLOCATOR(Duration);
 
@@ -109,41 +109,41 @@ struct CalendarNudgeResult {
     Crypto::BigFraction total;
 };
 
-DateDuration zero_date_duration(VM&);
-InternalDuration to_internal_duration_record(VM&, Duration const&);
-InternalDuration to_internal_duration_record_with_24_hour_days(VM&, Duration const&);
-DateDuration to_date_duration_record_without_time(VM&, Duration const&);
-ThrowCompletionOr<GC::Ref<Duration>> temporal_duration_from_internal(VM&, InternalDuration const&, Unit largest_unit);
-ThrowCompletionOr<DateDuration> create_date_duration_record(VM&, double years, double months, double weeks, double days);
-ThrowCompletionOr<DateDuration> adjust_date_duration_record(VM&, DateDuration const&, double days, Optional<double> weeks = {}, Optional<double> months = {});
-InternalDuration combine_date_and_time_duration(DateDuration, TimeDuration);
-ThrowCompletionOr<GC::Ref<Duration>> to_temporal_duration(VM&, Value);
-i8 duration_sign(Duration const&);
-i8 date_duration_sign(DateDuration const&);
-i8 internal_duration_sign(InternalDuration const&);
-bool is_valid_duration(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds);
-Unit default_temporal_largest_unit(Duration const&);
-ThrowCompletionOr<PartialDuration> to_temporal_partial_duration_record(VM&, Value temporal_duration_like);
-ThrowCompletionOr<GC::Ref<Duration>> create_temporal_duration(VM&, double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, GC::Ptr<FunctionObject> new_target = {});
-GC::Ref<Duration> create_negated_temporal_duration(VM&, Duration const&);
-TimeDuration time_duration_from_components(double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds);
-ThrowCompletionOr<TimeDuration> add_time_duration(VM&, TimeDuration const&, TimeDuration const&);
-ThrowCompletionOr<TimeDuration> add_24_hour_days_to_time_duration(VM&, TimeDuration const&, double days);
-Crypto::SignedBigInteger add_time_duration_to_epoch_nanoseconds(TimeDuration const& duration, Crypto::SignedBigInteger const& epoch_nanoseconds);
-i8 compare_time_duration(TimeDuration const&, TimeDuration const&);
-TimeDuration time_duration_from_epoch_nanoseconds_difference(Crypto::SignedBigInteger const&, Crypto::SignedBigInteger const&);
-ThrowCompletionOr<TimeDuration> round_time_duration_to_increment(VM&, TimeDuration const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
-i8 time_duration_sign(TimeDuration const&);
-ThrowCompletionOr<double> date_duration_days(VM&, DateDuration const&, PlainDate const&);
-ThrowCompletionOr<TimeDuration> round_time_duration(VM&, TimeDuration const&, Crypto::UnsignedBigInteger const& increment, Unit, RoundingMode);
-Crypto::BigFraction total_time_duration(TimeDuration const&, Unit);
-ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM&, i8 sign, InternalDuration const&, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
-ThrowCompletionOr<DurationNudgeResult> nudge_to_zoned_time(VM&, i8 sign, InternalDuration const&, ISODateTime const&, StringView time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
-ThrowCompletionOr<DurationNudgeResult> nudge_to_day_or_time(VM&, InternalDuration const&, Crypto::SignedBigInteger const& dest_epoch_ns, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode);
-ThrowCompletionOr<InternalDuration> bubble_relative_duration(VM&, i8 sign, InternalDuration, Crypto::SignedBigInteger const& nudged_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, Unit smallest_unit);
-ThrowCompletionOr<InternalDuration> round_relative_duration(VM&, InternalDuration, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode);
-ThrowCompletionOr<Crypto::BigFraction> total_relative_duration(VM&, InternalDuration const&, TimeDuration const&, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit);
-String temporal_duration_to_string(Duration const&, Precision);
-ThrowCompletionOr<GC::Ref<Duration>> add_durations(VM&, ArithmeticOperation, Duration const&, Value);
+JS_API DateDuration zero_date_duration(VM&);
+JS_API InternalDuration to_internal_duration_record(VM&, Duration const&);
+JS_API InternalDuration to_internal_duration_record_with_24_hour_days(VM&, Duration const&);
+JS_API DateDuration to_date_duration_record_without_time(VM&, Duration const&);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> temporal_duration_from_internal(VM&, InternalDuration const&, Unit largest_unit);
+JS_API ThrowCompletionOr<DateDuration> create_date_duration_record(VM&, double years, double months, double weeks, double days);
+JS_API ThrowCompletionOr<DateDuration> adjust_date_duration_record(VM&, DateDuration const&, double days, Optional<double> weeks = {}, Optional<double> months = {});
+JS_API InternalDuration combine_date_and_time_duration(DateDuration, TimeDuration);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> to_temporal_duration(VM&, Value);
+JS_API i8 duration_sign(Duration const&);
+JS_API i8 date_duration_sign(DateDuration const&);
+JS_API i8 internal_duration_sign(InternalDuration const&);
+JS_API bool is_valid_duration(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds);
+JS_API Unit default_temporal_largest_unit(Duration const&);
+JS_API ThrowCompletionOr<PartialDuration> to_temporal_partial_duration_record(VM&, Value temporal_duration_like);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> create_temporal_duration(VM&, double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, GC::Ptr<FunctionObject> new_target = {});
+JS_API GC::Ref<Duration> create_negated_temporal_duration(VM&, Duration const&);
+JS_API TimeDuration time_duration_from_components(double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds);
+JS_API ThrowCompletionOr<TimeDuration> add_time_duration(VM&, TimeDuration const&, TimeDuration const&);
+JS_API ThrowCompletionOr<TimeDuration> add_24_hour_days_to_time_duration(VM&, TimeDuration const&, double days);
+JS_API Crypto::SignedBigInteger add_time_duration_to_epoch_nanoseconds(TimeDuration const& duration, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API i8 compare_time_duration(TimeDuration const&, TimeDuration const&);
+JS_API TimeDuration time_duration_from_epoch_nanoseconds_difference(Crypto::SignedBigInteger const&, Crypto::SignedBigInteger const&);
+JS_API ThrowCompletionOr<TimeDuration> round_time_duration_to_increment(VM&, TimeDuration const&, Crypto::UnsignedBigInteger const& increment, RoundingMode);
+JS_API i8 time_duration_sign(TimeDuration const&);
+JS_API ThrowCompletionOr<double> date_duration_days(VM&, DateDuration const&, PlainDate const&);
+JS_API ThrowCompletionOr<TimeDuration> round_time_duration(VM&, TimeDuration const&, Crypto::UnsignedBigInteger const& increment, Unit, RoundingMode);
+JS_API Crypto::BigFraction total_time_duration(TimeDuration const&, Unit);
+JS_API ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM&, i8 sign, InternalDuration const&, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
+JS_API ThrowCompletionOr<DurationNudgeResult> nudge_to_zoned_time(VM&, i8 sign, InternalDuration const&, ISODateTime const&, StringView time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
+JS_API ThrowCompletionOr<DurationNudgeResult> nudge_to_day_or_time(VM&, InternalDuration const&, Crypto::SignedBigInteger const& dest_epoch_ns, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode);
+JS_API ThrowCompletionOr<InternalDuration> bubble_relative_duration(VM&, i8 sign, InternalDuration, Crypto::SignedBigInteger const& nudged_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, Unit smallest_unit);
+JS_API ThrowCompletionOr<InternalDuration> round_relative_duration(VM&, InternalDuration, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode);
+JS_API ThrowCompletionOr<Crypto::BigFraction> total_relative_duration(VM&, InternalDuration const&, TimeDuration const&, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, Unit);
+JS_API String temporal_duration_to_string(Duration const&, Precision);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> add_durations(VM&, ArithmeticOperation, Duration const&, Value);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/DurationConstructor.h b/Libraries/LibJS/Runtime/Temporal/DurationConstructor.h
index 2ffd47e4782..7527ad25b38 100644
--- a/Libraries/LibJS/Runtime/Temporal/DurationConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/DurationConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class DurationConstructor final : public NativeFunction {
+class JS_API DurationConstructor final : public NativeFunction {
     JS_OBJECT(DurationConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(DurationConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h b/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
index f6420de0f7a..94226a8b673 100644
--- a/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class DurationPrototype final : public PrototypeObject<DurationPrototype, Duration> {
+class JS_API DurationPrototype final : public PrototypeObject<DurationPrototype, Duration> {
     JS_PROTOTYPE_OBJECT(DurationPrototype, Duration, Temporal.Duration);
     GC_DECLARE_ALLOCATOR(DurationPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/ISO8601.h b/Libraries/LibJS/Runtime/Temporal/ISO8601.h
index 298732868e9..636fa789bad 100644
--- a/Libraries/LibJS/Runtime/Temporal/ISO8601.h
+++ b/Libraries/LibJS/Runtime/Temporal/ISO8601.h
@@ -72,13 +72,13 @@ enum class Production {
     TimeZoneIdentifier,
 };
 
-Optional<ParseResult> parse_iso8601(Production, StringView);
+JS_API Optional<ParseResult> parse_iso8601(Production, StringView);
 
 enum class SubMinutePrecision {
     No,
     Yes,
 };
 
-Optional<TimeZoneOffset> parse_utc_offset(StringView, SubMinutePrecision);
+JS_API Optional<TimeZoneOffset> parse_utc_offset(StringView, SubMinutePrecision);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/Instant.h b/Libraries/LibJS/Runtime/Temporal/Instant.h
index 6f87e9bc968..b9b1fc98d46 100644
--- a/Libraries/LibJS/Runtime/Temporal/Instant.h
+++ b/Libraries/LibJS/Runtime/Temporal/Instant.h
@@ -16,7 +16,7 @@
 
 namespace JS::Temporal {
 
-class Instant final : public Object {
+class JS_API Instant final : public Object {
     JS_OBJECT(Instant, Object);
     GC_DECLARE_ALLOCATOR(Instant);
 
@@ -56,15 +56,15 @@ extern Crypto::UnsignedBigInteger const SECONDS_PER_MINUTE;
 extern Crypto::UnsignedBigInteger const MINUTES_PER_HOUR;
 extern Crypto::UnsignedBigInteger const HOURS_PER_DAY;
 
-bool is_valid_epoch_nanoseconds(Crypto::SignedBigInteger const& epoch_nanoseconds);
-ThrowCompletionOr<GC::Ref<Instant>> create_temporal_instant(VM&, BigInt const& epoch_nanoseconds, GC::Ptr<FunctionObject> new_target = {});
-ThrowCompletionOr<GC::Ref<Instant>> to_temporal_instant(VM&, Value item);
-i8 compare_epoch_nanoseconds(Crypto::SignedBigInteger const& epoch_nanoseconds_one, Crypto::SignedBigInteger const& epoch_nanoseconds_two);
-ThrowCompletionOr<Crypto::SignedBigInteger> add_instant(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds, TimeDuration const&);
-InternalDuration difference_instant(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, u64 rounding_increment, Unit smallest_unit, RoundingMode);
-Crypto::SignedBigInteger round_temporal_instant(Crypto::SignedBigInteger const& nanoseconds, u64 increment, Unit, RoundingMode);
-String temporal_instant_to_string(Instant const&, Optional<StringView> time_zone, SecondsStringPrecision::Precision);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_instant(VM&, DurationOperation, Instant const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<Instant>> add_duration_to_instant(VM&, ArithmeticOperation, Instant const&, Value temporal_duration_like);
+JS_API bool is_valid_epoch_nanoseconds(Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API ThrowCompletionOr<GC::Ref<Instant>> create_temporal_instant(VM&, BigInt const& epoch_nanoseconds, GC::Ptr<FunctionObject> new_target = {});
+JS_API ThrowCompletionOr<GC::Ref<Instant>> to_temporal_instant(VM&, Value item);
+JS_API i8 compare_epoch_nanoseconds(Crypto::SignedBigInteger const& epoch_nanoseconds_one, Crypto::SignedBigInteger const& epoch_nanoseconds_two);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> add_instant(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds, TimeDuration const&);
+JS_API InternalDuration difference_instant(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, u64 rounding_increment, Unit smallest_unit, RoundingMode);
+JS_API Crypto::SignedBigInteger round_temporal_instant(Crypto::SignedBigInteger const& nanoseconds, u64 increment, Unit, RoundingMode);
+JS_API String temporal_instant_to_string(Instant const&, Optional<StringView> time_zone, SecondsStringPrecision::Precision);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_instant(VM&, DurationOperation, Instant const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<Instant>> add_duration_to_instant(VM&, ArithmeticOperation, Instant const&, Value temporal_duration_like);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h b/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h
index c5063e3a151..186c15f80bd 100644
--- a/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class InstantConstructor final : public NativeFunction {
+class JS_API InstantConstructor final : public NativeFunction {
     JS_OBJECT(InstantConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(InstantConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h b/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
index c06495bf50d..b8f7047752b 100644
--- a/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class InstantPrototype final : public PrototypeObject<InstantPrototype, Instant> {
+class JS_API InstantPrototype final : public PrototypeObject<InstantPrototype, Instant> {
     JS_PROTOTYPE_OBJECT(InstantPrototype, Instant, Temporal.Instant);
     GC_DECLARE_ALLOCATOR(InstantPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/Now.h b/Libraries/LibJS/Runtime/Temporal/Now.h
index 8c5bad0b381..fd6cf7dfd2a 100644
--- a/Libraries/LibJS/Runtime/Temporal/Now.h
+++ b/Libraries/LibJS/Runtime/Temporal/Now.h
@@ -13,7 +13,7 @@
 
 namespace JS::Temporal {
 
-class Now final : public Object {
+class JS_API Now final : public Object {
     JS_OBJECT(Now, Object);
     GC_DECLARE_ALLOCATOR(Now);
 
@@ -32,8 +32,8 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(plain_time_iso);
 };
 
-double system_utc_epoch_milliseconds(VM&);
-Crypto::SignedBigInteger system_utc_epoch_nanoseconds(VM&);
-ThrowCompletionOr<ISODateTime> system_date_time(VM&, Value temporal_time_zone_like);
+JS_API double system_utc_epoch_milliseconds(VM&);
+JS_API Crypto::SignedBigInteger system_utc_epoch_nanoseconds(VM&);
+JS_API ThrowCompletionOr<ISODateTime> system_date_time(VM&, Value temporal_time_zone_like);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDate.h b/Libraries/LibJS/Runtime/Temporal/PlainDate.h
index 694a3ed7590..2fbf364a137 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDate.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDate.h
@@ -17,7 +17,7 @@
 
 namespace JS::Temporal {
 
-class PlainDate final : public Object {
+class JS_API PlainDate final : public Object {
     JS_OBJECT(PlainDate, Object);
     GC_DECLARE_ALLOCATOR(PlainDate);
 
@@ -34,18 +34,18 @@ private:
     String m_calendar;  // [[Calendar]]
 };
 
-ISODate create_iso_date_record(double year, double month, double day);
-ThrowCompletionOr<GC::Ref<PlainDate>> to_temporal_date(VM& vm, Value item, Value options = js_undefined());
-ThrowCompletionOr<GC::Ref<PlainDate>> create_temporal_date(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
-bool iso_date_surpasses(i8 sign, double year1, double month1, double day1, ISODate iso_date2);
-ThrowCompletionOr<ISODate> regulate_iso_date(VM& vm, double year, double month, double day, Overflow overflow);
-bool is_valid_iso_date(double year, double month, double day);
-ISODate balance_iso_date(double year, double month, double day);
-String pad_iso_year(i32 year);
-String temporal_date_to_string(PlainDate const&, ShowCalendar);
-bool iso_date_within_limits(ISODate);
-i8 compare_iso_date(ISODate, ISODate);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_date(VM&, DurationOperation, PlainDate const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<PlainDate>> add_duration_to_date(VM&, ArithmeticOperation, PlainDate const&, Value temporal_duration_like, Value options);
+JS_API ISODate create_iso_date_record(double year, double month, double day);
+JS_API ThrowCompletionOr<GC::Ref<PlainDate>> to_temporal_date(VM& vm, Value item, Value options = js_undefined());
+JS_API ThrowCompletionOr<GC::Ref<PlainDate>> create_temporal_date(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
+JS_API bool iso_date_surpasses(i8 sign, double year1, double month1, double day1, ISODate iso_date2);
+JS_API ThrowCompletionOr<ISODate> regulate_iso_date(VM& vm, double year, double month, double day, Overflow overflow);
+JS_API bool is_valid_iso_date(double year, double month, double day);
+JS_API ISODate balance_iso_date(double year, double month, double day);
+JS_API String pad_iso_year(i32 year);
+JS_API String temporal_date_to_string(PlainDate const&, ShowCalendar);
+JS_API bool iso_date_within_limits(ISODate);
+JS_API i8 compare_iso_date(ISODate, ISODate);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_date(VM&, DurationOperation, PlainDate const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<PlainDate>> add_duration_to_date(VM&, ArithmeticOperation, PlainDate const&, Value temporal_duration_like, Value options);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h b/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
index 367f0252677..907f7d443b9 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class PlainDateConstructor final : public NativeFunction {
+class JS_API PlainDateConstructor final : public NativeFunction {
     JS_OBJECT(PlainDateConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PlainDateConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDatePrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainDatePrototype.h
index ca09df78348..a7f12411eae 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDatePrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDatePrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class PlainDatePrototype final : public PrototypeObject<PlainDatePrototype, PlainDate> {
+class JS_API PlainDatePrototype final : public PrototypeObject<PlainDatePrototype, PlainDate> {
     JS_PROTOTYPE_OBJECT(PlainDatePrototype, PlainDate, Temporal.PlainDate);
     GC_DECLARE_ALLOCATOR(PlainDatePrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h b/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
index f0d6107cb9a..d9c45e6ecf2 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDateTime.h
@@ -15,7 +15,7 @@
 
 namespace JS::Temporal {
 
-class PlainDateTime final : public Object {
+class JS_API PlainDateTime final : public Object {
     JS_OBJECT(PlainDateTime, Object);
     GC_DECLARE_ALLOCATOR(PlainDateTime);
 
@@ -32,20 +32,20 @@ private:
     String m_calendar;           // [[Calendar]]
 };
 
-ISODateTime time_value_to_iso_date_time_record(double time_value);
-ISODateTime combine_iso_date_and_time_record(ISODate, Time const&);
-bool iso_date_time_within_limits(ISODateTime const&);
-ThrowCompletionOr<ISODateTime> interpret_temporal_date_time_fields(VM&, StringView calendar, CalendarFields&, Overflow);
-ThrowCompletionOr<GC::Ref<PlainDateTime>> to_temporal_date_time(VM&, Value item, Value options = js_undefined());
-ISODateTime balance_iso_date_time(double year, double month, double day, double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
-ThrowCompletionOr<GC::Ref<PlainDateTime>> create_temporal_date_time(VM&, ISODateTime const&, String calendar, GC::Ptr<FunctionObject> new_target = {});
-String iso_date_time_to_string(ISODateTime const&, StringView calendar, SecondsStringPrecision::Precision, ShowCalendar);
-i8 compare_iso_date_time(ISODateTime const&, ISODateTime const&);
-ISODateTime round_iso_date_time(ISODateTime const&, u64 increment, Unit, RoundingMode);
-InternalDuration difference_iso_date_time(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit largest_unit);
-ThrowCompletionOr<InternalDuration> difference_plain_date_time_with_rounding(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit largest_unit, u64 rounding_increment, Unit smallest_unit, RoundingMode);
-ThrowCompletionOr<Crypto::BigFraction> difference_plain_date_time_with_total(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_date_time(VM&, DurationOperation, PlainDateTime const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<PlainDateTime>> add_duration_to_date_time(VM&, ArithmeticOperation, PlainDateTime const&, Value temporal_duration_like, Value options);
+JS_API ISODateTime time_value_to_iso_date_time_record(double time_value);
+JS_API ISODateTime combine_iso_date_and_time_record(ISODate, Time const&);
+JS_API bool iso_date_time_within_limits(ISODateTime const&);
+JS_API ThrowCompletionOr<ISODateTime> interpret_temporal_date_time_fields(VM&, StringView calendar, CalendarFields&, Overflow);
+JS_API ThrowCompletionOr<GC::Ref<PlainDateTime>> to_temporal_date_time(VM&, Value item, Value options = js_undefined());
+JS_API ISODateTime balance_iso_date_time(double year, double month, double day, double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
+JS_API ThrowCompletionOr<GC::Ref<PlainDateTime>> create_temporal_date_time(VM&, ISODateTime const&, String calendar, GC::Ptr<FunctionObject> new_target = {});
+JS_API String iso_date_time_to_string(ISODateTime const&, StringView calendar, SecondsStringPrecision::Precision, ShowCalendar);
+JS_API i8 compare_iso_date_time(ISODateTime const&, ISODateTime const&);
+JS_API ISODateTime round_iso_date_time(ISODateTime const&, u64 increment, Unit, RoundingMode);
+JS_API InternalDuration difference_iso_date_time(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit largest_unit);
+JS_API ThrowCompletionOr<InternalDuration> difference_plain_date_time_with_rounding(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit largest_unit, u64 rounding_increment, Unit smallest_unit, RoundingMode);
+JS_API ThrowCompletionOr<Crypto::BigFraction> difference_plain_date_time_with_total(VM&, ISODateTime const&, ISODateTime const&, StringView calendar, Unit);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_date_time(VM&, DurationOperation, PlainDateTime const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<PlainDateTime>> add_duration_to_date_time(VM&, ArithmeticOperation, PlainDateTime const&, Value temporal_duration_like, Value options);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDateTimeConstructor.h b/Libraries/LibJS/Runtime/Temporal/PlainDateTimeConstructor.h
index 75640dc3561..52686e669c0 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDateTimeConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDateTimeConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class PlainDateTimeConstructor final : public NativeFunction {
+class JS_API PlainDateTimeConstructor final : public NativeFunction {
     JS_OBJECT(PlainDateTimeConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PlainDateTimeConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
index 409fac63a07..5f39a8873ec 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class PlainDateTimePrototype final : public PrototypeObject<PlainDateTimePrototype, PlainDateTime> {
+class JS_API PlainDateTimePrototype final : public PrototypeObject<PlainDateTimePrototype, PlainDateTime> {
     JS_PROTOTYPE_OBJECT(PlainDateTimePrototype, PlainDateTime, Temporal.PlainDateTime);
     GC_DECLARE_ALLOCATOR(PlainDateTimePrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainMonthDay.h b/Libraries/LibJS/Runtime/Temporal/PlainMonthDay.h
index 0f2592240bc..b108d0bfef4 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainMonthDay.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainMonthDay.h
@@ -15,7 +15,7 @@
 
 namespace JS::Temporal {
 
-class PlainMonthDay final : public Object {
+class JS_API PlainMonthDay final : public Object {
     JS_OBJECT(PlainMonthDay, Object);
     GC_DECLARE_ALLOCATOR(PlainMonthDay);
 
@@ -32,8 +32,8 @@ private:
     String m_calendar;  // [[Calendar]]
 };
 
-ThrowCompletionOr<GC::Ref<PlainMonthDay>> to_temporal_month_day(VM&, Value item, Value options = js_undefined());
-ThrowCompletionOr<GC::Ref<PlainMonthDay>> create_temporal_month_day(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
-String temporal_month_day_to_string(PlainMonthDay const&, ShowCalendar);
+JS_API ThrowCompletionOr<GC::Ref<PlainMonthDay>> to_temporal_month_day(VM&, Value item, Value options = js_undefined());
+JS_API ThrowCompletionOr<GC::Ref<PlainMonthDay>> create_temporal_month_day(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
+JS_API String temporal_month_day_to_string(PlainMonthDay const&, ShowCalendar);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainMonthDayConstructor.h b/Libraries/LibJS/Runtime/Temporal/PlainMonthDayConstructor.h
index 03b81c0ceb2..ccdc992c559 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainMonthDayConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainMonthDayConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class PlainMonthDayConstructor final : public NativeFunction {
+class JS_API PlainMonthDayConstructor final : public NativeFunction {
     JS_OBJECT(PlainMonthDayConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PlainMonthDayConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.h
index ef74ed35113..adcd3d1eec6 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainMonthDayPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class PlainMonthDayPrototype final : public PrototypeObject<PlainMonthDayPrototype, PlainMonthDay> {
+class JS_API PlainMonthDayPrototype final : public PrototypeObject<PlainMonthDayPrototype, PlainMonthDay> {
     JS_PROTOTYPE_OBJECT(PlainMonthDayPrototype, PlainMonthDay, Temporal.PlainMonthDay);
     GC_DECLARE_ALLOCATOR(PlainMonthDayPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainTime.h b/Libraries/LibJS/Runtime/Temporal/PlainTime.h
index c8b93b1e953..bb03ae569a4 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainTime.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainTime.h
@@ -13,7 +13,7 @@
 
 namespace JS::Temporal {
 
-class PlainTime final : public Object {
+class JS_API PlainTime final : public Object {
     JS_OBJECT(PlainTime, Object);
     GC_DECLARE_ALLOCATOR(PlainTime);
 
@@ -48,23 +48,23 @@ enum class Completeness {
     Partial,
 };
 
-Time create_time_record(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond, double delta_days = 0);
-Time midnight_time_record();
-Time noon_time_record();
-TimeDuration difference_time(Time const&, Time const&);
-ThrowCompletionOr<GC::Ref<PlainTime>> to_temporal_time(VM&, Value item, Value options = js_undefined());
-ThrowCompletionOr<Time> to_time_record_or_midnight(VM&, Value item);
-ThrowCompletionOr<Time> regulate_time(VM&, double hour, double minute, double second, double millisecond, double microsecond, double nanosecond, Overflow);
-bool is_valid_time(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
-Time balance_time(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
-Time balance_time(double hour, double minute, double second, double millisecond, double microsecond, Crypto::SignedBigInteger const& nanosecond);
-ThrowCompletionOr<GC::Ref<PlainTime>> create_temporal_time(VM&, Time const&, GC::Ptr<FunctionObject> new_target = {});
-ThrowCompletionOr<TemporalTimeLike> to_temporal_time_record(VM&, Object const& temporal_time_like, Completeness = Completeness::Complete);
-String time_record_to_string(Time const&, SecondsStringPrecision::Precision);
-i8 compare_time_record(Time const&, Time const&);
-Time add_time(Time const&, TimeDuration const& time_duration);
-Time round_time(Time const&, u64 increment, Unit, RoundingMode);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_time(VM&, DurationOperation, PlainTime const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<PlainTime>> add_duration_to_time(VM&, ArithmeticOperation, PlainTime const&, Value temporal_duration_like);
+JS_API Time create_time_record(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond, double delta_days = 0);
+JS_API Time midnight_time_record();
+JS_API Time noon_time_record();
+JS_API TimeDuration difference_time(Time const&, Time const&);
+JS_API ThrowCompletionOr<GC::Ref<PlainTime>> to_temporal_time(VM&, Value item, Value options = js_undefined());
+JS_API ThrowCompletionOr<Time> to_time_record_or_midnight(VM&, Value item);
+JS_API ThrowCompletionOr<Time> regulate_time(VM&, double hour, double minute, double second, double millisecond, double microsecond, double nanosecond, Overflow);
+JS_API bool is_valid_time(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
+JS_API Time balance_time(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond);
+JS_API Time balance_time(double hour, double minute, double second, double millisecond, double microsecond, Crypto::SignedBigInteger const& nanosecond);
+JS_API ThrowCompletionOr<GC::Ref<PlainTime>> create_temporal_time(VM&, Time const&, GC::Ptr<FunctionObject> new_target = {});
+JS_API ThrowCompletionOr<TemporalTimeLike> to_temporal_time_record(VM&, Object const& temporal_time_like, Completeness = Completeness::Complete);
+JS_API String time_record_to_string(Time const&, SecondsStringPrecision::Precision);
+JS_API i8 compare_time_record(Time const&, Time const&);
+JS_API Time add_time(Time const&, TimeDuration const& time_duration);
+JS_API Time round_time(Time const&, u64 increment, Unit, RoundingMode);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_time(VM&, DurationOperation, PlainTime const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<PlainTime>> add_duration_to_time(VM&, ArithmeticOperation, PlainTime const&, Value temporal_duration_like);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainTimeConstructor.h b/Libraries/LibJS/Runtime/Temporal/PlainTimeConstructor.h
index 5c15fc86a37..5b74010400a 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainTimeConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainTimeConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class PlainTimeConstructor final : public NativeFunction {
+class JS_API PlainTimeConstructor final : public NativeFunction {
     JS_OBJECT(PlainTimeConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PlainTimeConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
index 7e680726507..973ee477c4d 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class PlainTimePrototype final : public PrototypeObject<PlainTimePrototype, PlainTime> {
+class JS_API PlainTimePrototype final : public PrototypeObject<PlainTimePrototype, PlainTime> {
     JS_PROTOTYPE_OBJECT(PlainTimePrototype, PlainTime, Temporal.PlainTime);
     GC_DECLARE_ALLOCATOR(PlainTimePrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainYearMonth.h b/Libraries/LibJS/Runtime/Temporal/PlainYearMonth.h
index fe54d60b667..ddcd880aa8c 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainYearMonth.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainYearMonth.h
@@ -16,7 +16,7 @@
 
 namespace JS::Temporal {
 
-class PlainYearMonth final : public Object {
+class JS_API PlainYearMonth final : public Object {
     JS_OBJECT(PlainYearMonth, Object);
     GC_DECLARE_ALLOCATOR(PlainYearMonth);
 
@@ -33,12 +33,12 @@ private:
     String m_calendar;  // [[Calendar]]
 };
 
-ThrowCompletionOr<GC::Ref<PlainYearMonth>> to_temporal_year_month(VM&, Value item, Value options = js_undefined());
-bool iso_year_month_within_limits(ISODate);
-ISOYearMonth balance_iso_year_month(double year, double month);
-ThrowCompletionOr<GC::Ref<PlainYearMonth>> create_temporal_year_month(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
-String temporal_year_month_to_string(PlainYearMonth const&, ShowCalendar);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_year_month(VM&, DurationOperation, PlainYearMonth const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<PlainYearMonth>> add_duration_to_year_month(VM&, ArithmeticOperation, PlainYearMonth const&, Value temporal_duration_like, Value options);
+JS_API ThrowCompletionOr<GC::Ref<PlainYearMonth>> to_temporal_year_month(VM&, Value item, Value options = js_undefined());
+JS_API bool iso_year_month_within_limits(ISODate);
+JS_API ISOYearMonth balance_iso_year_month(double year, double month);
+JS_API ThrowCompletionOr<GC::Ref<PlainYearMonth>> create_temporal_year_month(VM&, ISODate, String calendar, GC::Ptr<FunctionObject> new_target = {});
+JS_API String temporal_year_month_to_string(PlainYearMonth const&, ShowCalendar);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_plain_year_month(VM&, DurationOperation, PlainYearMonth const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<PlainYearMonth>> add_duration_to_year_month(VM&, ArithmeticOperation, PlainYearMonth const&, Value temporal_duration_like, Value options);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainYearMonthConstructor.h b/Libraries/LibJS/Runtime/Temporal/PlainYearMonthConstructor.h
index 41b966b3557..63893b32699 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainYearMonthConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainYearMonthConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class PlainYearMonthConstructor final : public NativeFunction {
+class JS_API PlainYearMonthConstructor final : public NativeFunction {
     JS_OBJECT(PlainYearMonthConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(PlainYearMonthConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
index af3e72cd7f5..f19e1e45d6a 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class PlainYearMonthPrototype final : public PrototypeObject<PlainYearMonthPrototype, PlainYearMonth> {
+class JS_API PlainYearMonthPrototype final : public PrototypeObject<PlainYearMonthPrototype, PlainYearMonth> {
     JS_PROTOTYPE_OBJECT(PlainYearMonthPrototype, PlainYearMonth, Temporal.PlainYearMonth);
     GC_DECLARE_ALLOCATOR(PlainYearMonthPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/Temporal.h b/Libraries/LibJS/Runtime/Temporal/Temporal.h
index 1265381ec88..ae188c7b6bb 100644
--- a/Libraries/LibJS/Runtime/Temporal/Temporal.h
+++ b/Libraries/LibJS/Runtime/Temporal/Temporal.h
@@ -10,7 +10,7 @@
 
 namespace JS::Temporal {
 
-class Temporal final : public Object {
+class JS_API Temporal final : public Object {
     JS_OBJECT(Temporal, Object);
     GC_DECLARE_ALLOCATOR(Temporal);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/TimeZone.h b/Libraries/LibJS/Runtime/Temporal/TimeZone.h
index 8035fce9f94..311c25c697e 100644
--- a/Libraries/LibJS/Runtime/Temporal/TimeZone.h
+++ b/Libraries/LibJS/Runtime/Temporal/TimeZone.h
@@ -21,23 +21,23 @@ struct TimeZone {
     Optional<i64> offset_minutes;
 };
 
-ISODateTime get_iso_parts_from_epoch(Crypto::SignedBigInteger const& epoch_nanoseconds);
-Optional<Crypto::SignedBigInteger> get_named_time_zone_next_transition(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
-Optional<Crypto::SignedBigInteger> get_named_time_zone_previous_transition(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
-String format_offset_time_zone_identifier(i64 offset_minutes, Optional<TimeStyle> = {});
-String format_utc_offset_nanoseconds(i64 offset_nanoseconds);
-String format_date_time_utc_offset_rounded(i64 offset_nanoseconds);
-ThrowCompletionOr<String> to_temporal_time_zone_identifier(VM&, Value temporal_time_zone_like);
-i64 get_offset_nanoseconds_for(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
-ISODateTime get_iso_date_time_for(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
-ThrowCompletionOr<String> to_temporal_time_zone_identifier(VM&, StringView temporal_time_zone_like);
-ThrowCompletionOr<Crypto::SignedBigInteger> get_epoch_nanoseconds_for(VM&, StringView time_zone, ISODateTime const&, Disambiguation);
-ThrowCompletionOr<Crypto::SignedBigInteger> disambiguate_possible_epoch_nanoseconds(VM&, Vector<Crypto::SignedBigInteger> possible_epoch_ns, StringView time_zone, ISODateTime const&, Disambiguation);
-ThrowCompletionOr<Vector<Crypto::SignedBigInteger>> get_possible_epoch_nanoseconds(VM&, StringView time_zone, ISODateTime const&);
-ThrowCompletionOr<Crypto::SignedBigInteger> get_start_of_day(VM&, StringView time_zone, ISODate);
-bool time_zone_equals(StringView one, StringView two);
-ThrowCompletionOr<TimeZone> parse_time_zone_identifier(VM&, StringView identifier);
-TimeZone parse_time_zone_identifier(StringView identifier);
-TimeZone parse_time_zone_identifier(ParseResult const&);
+JS_API ISODateTime get_iso_parts_from_epoch(Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API Optional<Crypto::SignedBigInteger> get_named_time_zone_next_transition(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API Optional<Crypto::SignedBigInteger> get_named_time_zone_previous_transition(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API String format_offset_time_zone_identifier(i64 offset_minutes, Optional<TimeStyle> = {});
+JS_API String format_utc_offset_nanoseconds(i64 offset_nanoseconds);
+JS_API String format_date_time_utc_offset_rounded(i64 offset_nanoseconds);
+JS_API ThrowCompletionOr<String> to_temporal_time_zone_identifier(VM&, Value temporal_time_zone_like);
+JS_API i64 get_offset_nanoseconds_for(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API ISODateTime get_iso_date_time_for(StringView time_zone, Crypto::SignedBigInteger const& epoch_nanoseconds);
+JS_API ThrowCompletionOr<String> to_temporal_time_zone_identifier(VM&, StringView temporal_time_zone_like);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> get_epoch_nanoseconds_for(VM&, StringView time_zone, ISODateTime const&, Disambiguation);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> disambiguate_possible_epoch_nanoseconds(VM&, Vector<Crypto::SignedBigInteger> possible_epoch_ns, StringView time_zone, ISODateTime const&, Disambiguation);
+JS_API ThrowCompletionOr<Vector<Crypto::SignedBigInteger>> get_possible_epoch_nanoseconds(VM&, StringView time_zone, ISODateTime const&);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> get_start_of_day(VM&, StringView time_zone, ISODate);
+JS_API bool time_zone_equals(StringView one, StringView two);
+JS_API ThrowCompletionOr<TimeZone> parse_time_zone_identifier(VM&, StringView identifier);
+JS_API TimeZone parse_time_zone_identifier(StringView identifier);
+JS_API TimeZone parse_time_zone_identifier(ParseResult const&);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/ZonedDateTime.h b/Libraries/LibJS/Runtime/Temporal/ZonedDateTime.h
index 45e15445547..8adf816a94d 100644
--- a/Libraries/LibJS/Runtime/Temporal/ZonedDateTime.h
+++ b/Libraries/LibJS/Runtime/Temporal/ZonedDateTime.h
@@ -16,7 +16,7 @@
 
 namespace JS::Temporal {
 
-class ZonedDateTime final : public Object {
+class JS_API ZonedDateTime final : public Object {
     JS_OBJECT(ZonedDateTime, Object);
     GC_DECLARE_ALLOCATOR(ZonedDateTime);
 
@@ -48,15 +48,15 @@ enum class MatchBehavior {
     MatchMinutes,
 };
 
-ThrowCompletionOr<Crypto::SignedBigInteger> interpret_iso_date_time_offset(VM&, ISODate, Variant<ParsedISODateTime::StartOfDay, Time> const&, OffsetBehavior, double offset_nanoseconds, StringView time_zone, Disambiguation, OffsetOption, MatchBehavior);
-ThrowCompletionOr<GC::Ref<ZonedDateTime>> to_temporal_zoned_date_time(VM&, Value item, Value options = js_undefined());
-ThrowCompletionOr<GC::Ref<ZonedDateTime>> create_temporal_zoned_date_time(VM&, BigInt const& epoch_nanoseconds, String time_zone, String calendar, GC::Ptr<FunctionObject> new_target = {});
-String temporal_zoned_date_time_to_string(ZonedDateTime const&, SecondsStringPrecision::Precision, ShowCalendar, ShowTimeZoneName, ShowOffset, u64 increment = 1, Unit = Unit::Nanosecond, RoundingMode = RoundingMode::Trunc);
-ThrowCompletionOr<Crypto::SignedBigInteger> add_zoned_date_time(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds, StringView time_zone, StringView calendar, InternalDuration const&, Overflow);
-ThrowCompletionOr<InternalDuration> difference_zoned_date_time(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit largest_unit);
-ThrowCompletionOr<InternalDuration> difference_zoned_date_time_with_rounding(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit largest_unit, u64 rounding_increment, Unit smallest_unit, RoundingMode);
-ThrowCompletionOr<Crypto::BigFraction> difference_zoned_date_time_with_total(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit);
-ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_zoned_date_time(VM&, DurationOperation, ZonedDateTime const&, Value other, Value options);
-ThrowCompletionOr<GC::Ref<ZonedDateTime>> add_duration_to_zoned_date_time(VM&, ArithmeticOperation, ZonedDateTime const&, Value temporal_duration_like, Value options);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> interpret_iso_date_time_offset(VM&, ISODate, Variant<ParsedISODateTime::StartOfDay, Time> const&, OffsetBehavior, double offset_nanoseconds, StringView time_zone, Disambiguation, OffsetOption, MatchBehavior);
+JS_API ThrowCompletionOr<GC::Ref<ZonedDateTime>> to_temporal_zoned_date_time(VM&, Value item, Value options = js_undefined());
+JS_API ThrowCompletionOr<GC::Ref<ZonedDateTime>> create_temporal_zoned_date_time(VM&, BigInt const& epoch_nanoseconds, String time_zone, String calendar, GC::Ptr<FunctionObject> new_target = {});
+JS_API String temporal_zoned_date_time_to_string(ZonedDateTime const&, SecondsStringPrecision::Precision, ShowCalendar, ShowTimeZoneName, ShowOffset, u64 increment = 1, Unit = Unit::Nanosecond, RoundingMode = RoundingMode::Trunc);
+JS_API ThrowCompletionOr<Crypto::SignedBigInteger> add_zoned_date_time(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds, StringView time_zone, StringView calendar, InternalDuration const&, Overflow);
+JS_API ThrowCompletionOr<InternalDuration> difference_zoned_date_time(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit largest_unit);
+JS_API ThrowCompletionOr<InternalDuration> difference_zoned_date_time_with_rounding(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit largest_unit, u64 rounding_increment, Unit smallest_unit, RoundingMode);
+JS_API ThrowCompletionOr<Crypto::BigFraction> difference_zoned_date_time_with_total(VM&, Crypto::SignedBigInteger const& nanoseconds1, Crypto::SignedBigInteger const& nanoseconds2, StringView time_zone, StringView calendar, Unit);
+JS_API ThrowCompletionOr<GC::Ref<Duration>> difference_temporal_zoned_date_time(VM&, DurationOperation, ZonedDateTime const&, Value other, Value options);
+JS_API ThrowCompletionOr<GC::Ref<ZonedDateTime>> add_duration_to_zoned_date_time(VM&, ArithmeticOperation, ZonedDateTime const&, Value temporal_duration_like, Value options);
 
 }
diff --git a/Libraries/LibJS/Runtime/Temporal/ZonedDateTimeConstructor.h b/Libraries/LibJS/Runtime/Temporal/ZonedDateTimeConstructor.h
index fcd9970a688..cea88a6a0b3 100644
--- a/Libraries/LibJS/Runtime/Temporal/ZonedDateTimeConstructor.h
+++ b/Libraries/LibJS/Runtime/Temporal/ZonedDateTimeConstructor.h
@@ -11,7 +11,7 @@
 
 namespace JS::Temporal {
 
-class ZonedDateTimeConstructor final : public NativeFunction {
+class JS_API ZonedDateTimeConstructor final : public NativeFunction {
     JS_OBJECT(ZonedDateTimeConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(ZonedDateTimeConstructor);
 
diff --git a/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.h b/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.h
index 2cc64caf286..b6b545d6159 100644
--- a/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS::Temporal {
 
-class ZonedDateTimePrototype final : public PrototypeObject<ZonedDateTimePrototype, ZonedDateTime> {
+class JS_API ZonedDateTimePrototype final : public PrototypeObject<ZonedDateTimePrototype, ZonedDateTime> {
     JS_PROTOTYPE_OBJECT(ZonedDateTimePrototype, ZonedDateTime, Temporal.ZonedDateTime);
     GC_DECLARE_ALLOCATOR(ZonedDateTimePrototype);
 
diff --git a/Libraries/LibJS/Runtime/TypedArray.h b/Libraries/LibJS/Runtime/TypedArray.h
index 4473b4fb5f8..783e805aea4 100644
--- a/Libraries/LibJS/Runtime/TypedArray.h
+++ b/Libraries/LibJS/Runtime/TypedArray.h
@@ -19,7 +19,7 @@
 
 namespace JS {
 
-class TypedArrayBase : public Object {
+class JS_API TypedArrayBase : public Object {
     JS_OBJECT(TypedArrayBase, Object);
 
 public:
@@ -91,12 +91,12 @@ struct TypedArrayWithBufferWitness {
     ByteLength cached_buffer_byte_length; // [[CachedBufferByteLength]]
 };
 
-TypedArrayWithBufferWitness make_typed_array_with_buffer_witness_record(TypedArrayBase const&, ArrayBuffer::Order);
-u32 typed_array_byte_length(TypedArrayWithBufferWitness const&);
-u32 typed_array_length(TypedArrayWithBufferWitness const&);
-bool is_typed_array_out_of_bounds(TypedArrayWithBufferWitness const&);
-bool is_typed_array_fixed_length(TypedArrayBase const&);
-bool is_valid_integer_index_slow_case(TypedArrayBase const&, CanonicalIndex property_index);
+JS_API TypedArrayWithBufferWitness make_typed_array_with_buffer_witness_record(TypedArrayBase const&, ArrayBuffer::Order);
+JS_API u32 typed_array_byte_length(TypedArrayWithBufferWitness const&);
+JS_API u32 typed_array_length(TypedArrayWithBufferWitness const&);
+JS_API bool is_typed_array_out_of_bounds(TypedArrayWithBufferWitness const&);
+JS_API bool is_typed_array_fixed_length(TypedArrayBase const&);
+JS_API bool is_valid_integer_index_slow_case(TypedArrayBase const&, CanonicalIndex property_index);
 
 // 10.4.5.16 IsValidIntegerIndex ( O, index ), https://tc39.es/ecma262/#sec-isvalidintegerindex
 inline bool is_valid_integer_index(TypedArrayBase const& typed_array, CanonicalIndex property_index)
@@ -507,14 +507,14 @@ protected:
     }
 };
 
-ThrowCompletionOr<TypedArrayBase*> typed_array_from(VM&, Value);
-ThrowCompletionOr<TypedArrayBase*> typed_array_create(VM&, FunctionObject& constructor, GC::RootVector<Value> arguments);
-ThrowCompletionOr<TypedArrayBase*> typed_array_create_same_type(VM&, TypedArrayBase const& exemplar, GC::RootVector<Value> arguments);
-ThrowCompletionOr<TypedArrayWithBufferWitness> validate_typed_array(VM&, Object const&, ArrayBuffer::Order);
-ThrowCompletionOr<double> compare_typed_array_elements(VM&, Value x, Value y, FunctionObject* comparefn);
+JS_API ThrowCompletionOr<TypedArrayBase*> typed_array_from(VM&, Value);
+JS_API ThrowCompletionOr<TypedArrayBase*> typed_array_create(VM&, FunctionObject& constructor, GC::RootVector<Value> arguments);
+JS_API ThrowCompletionOr<TypedArrayBase*> typed_array_create_same_type(VM&, TypedArrayBase const& exemplar, GC::RootVector<Value> arguments);
+JS_API ThrowCompletionOr<TypedArrayWithBufferWitness> validate_typed_array(VM&, Object const&, ArrayBuffer::Order);
+JS_API ThrowCompletionOr<double> compare_typed_array_elements(VM&, Value x, Value y, FunctionObject* comparefn);
 
 #define JS_DECLARE_TYPED_ARRAY(ClassName, snake_name, PrototypeName, ConstructorName, Type)                  \
-    class ClassName : public TypedArray<Type> {                                                              \
+    class JS_API ClassName : public TypedArray<Type> {                                                       \
         JS_OBJECT(ClassName, TypedArray);                                                                    \
         GC_DECLARE_ALLOCATOR(ClassName);                                                                     \
                                                                                                              \
diff --git a/Libraries/LibJS/Runtime/TypedArrayConstructor.h b/Libraries/LibJS/Runtime/TypedArrayConstructor.h
index 3490b86b8dc..41b4b2a0d6a 100644
--- a/Libraries/LibJS/Runtime/TypedArrayConstructor.h
+++ b/Libraries/LibJS/Runtime/TypedArrayConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class TypedArrayConstructor : public NativeFunction {
+class JS_API TypedArrayConstructor : public NativeFunction {
     JS_OBJECT(TypedArrayConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(TypedArrayConstructor);
 
diff --git a/Libraries/LibJS/Runtime/TypedArrayPrototype.h b/Libraries/LibJS/Runtime/TypedArrayPrototype.h
index eeb777d8159..c5458d864ab 100644
--- a/Libraries/LibJS/Runtime/TypedArrayPrototype.h
+++ b/Libraries/LibJS/Runtime/TypedArrayPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class TypedArrayPrototype final : public Object {
+class JS_API TypedArrayPrototype final : public Object {
     JS_OBJECT(TypedArrayPrototype, Object);
     GC_DECLARE_ALLOCATOR(TypedArrayPrototype);
 
diff --git a/Libraries/LibJS/Runtime/Uint8Array.h b/Libraries/LibJS/Runtime/Uint8Array.h
index 59d7ee846df..007d8bb7454 100644
--- a/Libraries/LibJS/Runtime/Uint8Array.h
+++ b/Libraries/LibJS/Runtime/Uint8Array.h
@@ -17,7 +17,7 @@
 
 namespace JS {
 
-class Uint8ArrayConstructorHelpers {
+class JS_API Uint8ArrayConstructorHelpers {
 public:
     static void initialize(Realm&, Object& constructor);
 
@@ -26,7 +26,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(from_hex);
 };
 
-class Uint8ArrayPrototypeHelpers {
+class JS_API Uint8ArrayPrototypeHelpers {
 public:
     static void initialize(Realm&, Object& prototype);
 
@@ -48,10 +48,10 @@ struct DecodeResult {
     Optional<Completion> error; // [[Error]]
 };
 
-ThrowCompletionOr<GC::Ref<TypedArrayBase>> validate_uint8_array(VM&);
-ThrowCompletionOr<ByteBuffer> get_uint8_array_bytes(VM&, TypedArrayBase const&);
-void set_uint8_array_bytes(TypedArrayBase&, ReadonlyBytes);
-DecodeResult from_base64(VM&, StringView string, Alphabet alphabet, AK::LastChunkHandling last_chunk_handling, Optional<size_t> max_length = {});
-DecodeResult from_hex(VM&, StringView string, Optional<size_t> max_length = {});
+JS_API ThrowCompletionOr<GC::Ref<TypedArrayBase>> validate_uint8_array(VM&);
+JS_API ThrowCompletionOr<ByteBuffer> get_uint8_array_bytes(VM&, TypedArrayBase const&);
+JS_API void set_uint8_array_bytes(TypedArrayBase&, ReadonlyBytes);
+JS_API DecodeResult from_base64(VM&, StringView string, Alphabet alphabet, AK::LastChunkHandling last_chunk_handling, Optional<size_t> max_length = {});
+JS_API DecodeResult from_hex(VM&, StringView string, Optional<size_t> max_length = {});
 
 }
diff --git a/Libraries/LibJS/Runtime/Utf16String.h b/Libraries/LibJS/Runtime/Utf16String.h
index 5892daa64a7..4e9fe940ce2 100644
--- a/Libraries/LibJS/Runtime/Utf16String.h
+++ b/Libraries/LibJS/Runtime/Utf16String.h
@@ -17,7 +17,7 @@
 namespace JS {
 namespace Detail {
 
-class Utf16StringImpl : public RefCounted<Utf16StringImpl> {
+class JS_API Utf16StringImpl : public RefCounted<Utf16StringImpl> {
 public:
     ~Utf16StringImpl() = default;
 
@@ -53,7 +53,7 @@ private:
 
 }
 
-class Utf16String {
+class JS_API Utf16String {
 public:
     [[nodiscard]] static Utf16String create();
     [[nodiscard]] static Utf16String create(Utf16Data);
diff --git a/Libraries/LibJS/Runtime/VM.h b/Libraries/LibJS/Runtime/VM.h
index ebf903bd7a9..c8ea2b81128 100644
--- a/Libraries/LibJS/Runtime/VM.h
+++ b/Libraries/LibJS/Runtime/VM.h
@@ -45,7 +45,7 @@ enum class EvalMode {
     Indirect
 };
 
-class VM : public RefCounted<VM> {
+class JS_API VM : public RefCounted<VM> {
 public:
     static NonnullRefPtr<VM> create();
     ~VM();
diff --git a/Libraries/LibJS/Runtime/Value.h b/Libraries/LibJS/Runtime/Value.h
index 7e22d96cbc3..cce9cd1b554 100644
--- a/Libraries/LibJS/Runtime/Value.h
+++ b/Libraries/LibJS/Runtime/Value.h
@@ -85,7 +85,7 @@ static constexpr u64 SHIFTED_INT32_TAG = INT32_TAG << GC::TAG_SHIFT;
 // options from 8 tags to 15 but since we currently only use 5 for both sign bits
 // this is not needed.
 
-class Value : public GC::NanBoxedValue {
+class JS_API Value : public GC::NanBoxedValue {
 public:
     enum class PreferredType {
         Default,
@@ -458,15 +458,15 @@ private:
 
     ThrowCompletionOr<i32> to_i32_slow_case(VM&) const;
 
-    friend constexpr Value js_undefined();
-    friend constexpr Value js_null();
-    friend constexpr Value js_special_empty_value();
-    friend ThrowCompletionOr<bool> greater_than(VM&, Value lhs, Value rhs);
-    friend ThrowCompletionOr<bool> greater_than_equals(VM&, Value lhs, Value rhs);
-    friend ThrowCompletionOr<bool> less_than(VM&, Value lhs, Value rhs);
-    friend ThrowCompletionOr<bool> less_than_equals(VM&, Value lhs, Value rhs);
-    friend ThrowCompletionOr<Value> add(VM&, Value lhs, Value rhs);
-    friend bool same_value_non_number(Value lhs, Value rhs);
+    JS_API friend constexpr Value js_undefined();
+    JS_API friend constexpr Value js_null();
+    JS_API friend constexpr Value js_special_empty_value();
+    JS_API friend ThrowCompletionOr<bool> greater_than(VM&, Value lhs, Value rhs);
+    JS_API friend ThrowCompletionOr<bool> greater_than_equals(VM&, Value lhs, Value rhs);
+    JS_API friend ThrowCompletionOr<bool> less_than(VM&, Value lhs, Value rhs);
+    JS_API friend ThrowCompletionOr<bool> less_than_equals(VM&, Value lhs, Value rhs);
+    JS_API friend ThrowCompletionOr<Value> add(VM&, Value lhs, Value rhs);
+    JS_API friend bool same_value_non_number(Value lhs, Value rhs);
 };
 
 inline constexpr Value js_undefined()
@@ -499,45 +499,45 @@ inline Value js_negative_infinity()
     return Value(-INFINITY);
 }
 
-ThrowCompletionOr<bool> greater_than(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<bool> greater_than_equals(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<bool> less_than(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<bool> less_than_equals(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> bitwise_and(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> bitwise_or(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> bitwise_xor(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> bitwise_not(VM&, Value);
-ThrowCompletionOr<Value> unary_plus(VM&, Value);
-ThrowCompletionOr<Value> unary_minus(VM&, Value);
-ThrowCompletionOr<Value> left_shift(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> right_shift(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> unsigned_right_shift(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> add(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> sub(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> mul(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> div(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> mod(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> exp(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> in(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> instance_of(VM&, Value lhs, Value rhs);
-ThrowCompletionOr<Value> ordinary_has_instance(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<bool> greater_than(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<bool> greater_than_equals(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<bool> less_than(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<bool> less_than_equals(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> bitwise_and(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> bitwise_or(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> bitwise_xor(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> bitwise_not(VM&, Value);
+JS_API ThrowCompletionOr<Value> unary_plus(VM&, Value);
+JS_API ThrowCompletionOr<Value> unary_minus(VM&, Value);
+JS_API ThrowCompletionOr<Value> left_shift(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> right_shift(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> unsigned_right_shift(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> add(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> sub(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> mul(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> div(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> mod(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> exp(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> in(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> instance_of(VM&, Value lhs, Value rhs);
+JS_API ThrowCompletionOr<Value> ordinary_has_instance(VM&, Value lhs, Value rhs);
 
-ThrowCompletionOr<bool> is_loosely_equal(VM&, Value lhs, Value rhs);
-bool is_strictly_equal(Value lhs, Value rhs);
-bool same_value(Value lhs, Value rhs);
-bool same_value_zero(Value lhs, Value rhs);
-bool same_value_non_number(Value lhs, Value rhs);
-ThrowCompletionOr<TriState> is_less_than(VM&, Value lhs, Value rhs, bool left_first);
+JS_API ThrowCompletionOr<bool> is_loosely_equal(VM&, Value lhs, Value rhs);
+JS_API bool is_strictly_equal(Value lhs, Value rhs);
+JS_API bool same_value(Value lhs, Value rhs);
+JS_API bool same_value_zero(Value lhs, Value rhs);
+JS_API bool same_value_non_number(Value lhs, Value rhs);
+JS_API ThrowCompletionOr<TriState> is_less_than(VM&, Value lhs, Value rhs, bool left_first);
 
-double to_integer_or_infinity(double);
+JS_API double to_integer_or_infinity(double);
 
 enum class NumberToStringMode {
     WithExponent,
     WithoutExponent,
 };
-[[nodiscard]] String number_to_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
-[[nodiscard]] ByteString number_to_byte_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
-double string_to_number(StringView);
+[[nodiscard]] JS_API String number_to_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
+[[nodiscard]] JS_API ByteString number_to_byte_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
+JS_API double string_to_number(StringView);
 
 inline bool Value::operator==(Value const& value) const { return same_value(*this, value); }
 
diff --git a/Libraries/LibJS/Runtime/WeakMap.h b/Libraries/LibJS/Runtime/WeakMap.h
index 20352146a64..61de5160708 100644
--- a/Libraries/LibJS/Runtime/WeakMap.h
+++ b/Libraries/LibJS/Runtime/WeakMap.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class WeakMap final
+class JS_API WeakMap final
     : public Object
     , public GC::WeakContainer {
     JS_OBJECT(WeakMap, Object);
diff --git a/Libraries/LibJS/Runtime/WeakMapConstructor.h b/Libraries/LibJS/Runtime/WeakMapConstructor.h
index 25d59ae6c6b..9b14c4df537 100644
--- a/Libraries/LibJS/Runtime/WeakMapConstructor.h
+++ b/Libraries/LibJS/Runtime/WeakMapConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class WeakMapConstructor final : public NativeFunction {
+class JS_API WeakMapConstructor final : public NativeFunction {
     JS_OBJECT(WeakMapConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(WeakMapConstructor);
 
diff --git a/Libraries/LibJS/Runtime/WeakMapPrototype.h b/Libraries/LibJS/Runtime/WeakMapPrototype.h
index c4969f8681d..78da386b3a2 100644
--- a/Libraries/LibJS/Runtime/WeakMapPrototype.h
+++ b/Libraries/LibJS/Runtime/WeakMapPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class WeakMapPrototype final : public PrototypeObject<WeakMapPrototype, WeakMap> {
+class JS_API WeakMapPrototype final : public PrototypeObject<WeakMapPrototype, WeakMap> {
     JS_PROTOTYPE_OBJECT(WeakMapPrototype, WeakMap, WeakMap);
     GC_DECLARE_ALLOCATOR(WeakMapPrototype);
 
diff --git a/Libraries/LibJS/Runtime/WeakRef.h b/Libraries/LibJS/Runtime/WeakRef.h
index c0f38cdff79..c9f7d2e1b0f 100644
--- a/Libraries/LibJS/Runtime/WeakRef.h
+++ b/Libraries/LibJS/Runtime/WeakRef.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class WeakRef final
+class JS_API WeakRef final
     : public Object
     , public GC::WeakContainer {
     JS_OBJECT(WeakRef, Object);
diff --git a/Libraries/LibJS/Runtime/WeakRefConstructor.h b/Libraries/LibJS/Runtime/WeakRefConstructor.h
index e1f7fef86d4..0106aefd45e 100644
--- a/Libraries/LibJS/Runtime/WeakRefConstructor.h
+++ b/Libraries/LibJS/Runtime/WeakRefConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class WeakRefConstructor final : public NativeFunction {
+class JS_API WeakRefConstructor final : public NativeFunction {
     JS_OBJECT(WeakRefConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(WeakRefConstructor);
 
diff --git a/Libraries/LibJS/Runtime/WeakRefPrototype.h b/Libraries/LibJS/Runtime/WeakRefPrototype.h
index 2279e17b47b..1cfcc3feade 100644
--- a/Libraries/LibJS/Runtime/WeakRefPrototype.h
+++ b/Libraries/LibJS/Runtime/WeakRefPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class WeakRefPrototype final : public PrototypeObject<WeakRefPrototype, WeakRef> {
+class JS_API WeakRefPrototype final : public PrototypeObject<WeakRefPrototype, WeakRef> {
     JS_PROTOTYPE_OBJECT(WeakRefPrototype, WeakRef, WeakRef);
     GC_DECLARE_ALLOCATOR(WeakRefPrototype);
 
diff --git a/Libraries/LibJS/Runtime/WeakSet.h b/Libraries/LibJS/Runtime/WeakSet.h
index 1489f83582f..e706e7c0923 100644
--- a/Libraries/LibJS/Runtime/WeakSet.h
+++ b/Libraries/LibJS/Runtime/WeakSet.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class WeakSet final
+class JS_API WeakSet final
     : public Object
     , public GC::WeakContainer {
     JS_OBJECT(WeakSet, Object);
diff --git a/Libraries/LibJS/Runtime/WeakSetConstructor.h b/Libraries/LibJS/Runtime/WeakSetConstructor.h
index da8bd61b021..6e6059dac32 100644
--- a/Libraries/LibJS/Runtime/WeakSetConstructor.h
+++ b/Libraries/LibJS/Runtime/WeakSetConstructor.h
@@ -10,7 +10,7 @@
 
 namespace JS {
 
-class WeakSetConstructor final : public NativeFunction {
+class JS_API WeakSetConstructor final : public NativeFunction {
     JS_OBJECT(WeakSetConstructor, NativeFunction);
     GC_DECLARE_ALLOCATOR(WeakSetConstructor);
 
diff --git a/Libraries/LibJS/Runtime/WeakSetPrototype.h b/Libraries/LibJS/Runtime/WeakSetPrototype.h
index d3e1bb5bcba..e125302d3f8 100644
--- a/Libraries/LibJS/Runtime/WeakSetPrototype.h
+++ b/Libraries/LibJS/Runtime/WeakSetPrototype.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class WeakSetPrototype final : public PrototypeObject<WeakSetPrototype, WeakSet> {
+class JS_API WeakSetPrototype final : public PrototypeObject<WeakSetPrototype, WeakSet> {
     JS_PROTOTYPE_OBJECT(WeakSetPrototype, WeakSet, WeakSet);
     GC_DECLARE_ALLOCATOR(WeakSetPrototype);
 
diff --git a/Libraries/LibJS/Runtime/WrapForValidIteratorPrototype.h b/Libraries/LibJS/Runtime/WrapForValidIteratorPrototype.h
index 43bc5a94734..1bb6f508ee9 100644
--- a/Libraries/LibJS/Runtime/WrapForValidIteratorPrototype.h
+++ b/Libraries/LibJS/Runtime/WrapForValidIteratorPrototype.h
@@ -12,7 +12,7 @@
 
 namespace JS {
 
-class WrapForValidIteratorPrototype final : public PrototypeObject<WrapForValidIteratorPrototype, Iterator> {
+class JS_API WrapForValidIteratorPrototype final : public PrototypeObject<WrapForValidIteratorPrototype, Iterator> {
     JS_PROTOTYPE_OBJECT(WrapForValidIteratorPrototype, Iterator, Iterator);
     GC_DECLARE_ALLOCATOR(WrapForValidIteratorPrototype);
 
diff --git a/Libraries/LibJS/Runtime/WrappedFunction.h b/Libraries/LibJS/Runtime/WrappedFunction.h
index 86bc0a7c95c..4484447964d 100644
--- a/Libraries/LibJS/Runtime/WrappedFunction.h
+++ b/Libraries/LibJS/Runtime/WrappedFunction.h
@@ -11,7 +11,7 @@
 
 namespace JS {
 
-class WrappedFunction final : public FunctionObject {
+class JS_API WrappedFunction final : public FunctionObject {
     JS_OBJECT(WrappedFunction, FunctionObject);
     GC_DECLARE_ALLOCATOR(WrappedFunction);
 
diff --git a/Libraries/LibJS/Script.h b/Libraries/LibJS/Script.h
index aabb896d31c..a95020a581c 100644
--- a/Libraries/LibJS/Script.h
+++ b/Libraries/LibJS/Script.h
@@ -15,7 +15,7 @@
 namespace JS {
 
 // 16.1.4 Script Records, https://tc39.es/ecma262/#sec-script-records
-class Script final : public Cell {
+class JS_API Script final : public Cell {
     GC_CELL(Script, Cell);
     GC_DECLARE_ALLOCATOR(Script);
 
diff --git a/Libraries/LibJS/SourceCode.h b/Libraries/LibJS/SourceCode.h
index 229f7443a40..f509c87a45d 100644
--- a/Libraries/LibJS/SourceCode.h
+++ b/Libraries/LibJS/SourceCode.h
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-class SourceCode : public RefCounted<SourceCode> {
+class JS_API SourceCode : public RefCounted<SourceCode> {
 public:
     static NonnullRefPtr<SourceCode const> create(String filename, String code);
 
diff --git a/Libraries/LibJS/SourceRange.h b/Libraries/LibJS/SourceRange.h
index e0fe5baa7da..f42036e9f36 100644
--- a/Libraries/LibJS/SourceRange.h
+++ b/Libraries/LibJS/SourceRange.h
@@ -15,7 +15,7 @@
 
 namespace JS {
 
-struct SourceRange {
+struct JS_API SourceRange {
     [[nodiscard]] bool contains(Position const& position) const { return position.offset <= end.offset && position.offset >= start.offset; }
 
     NonnullRefPtr<SourceCode const> code;
diff --git a/Libraries/LibJS/SourceTextModule.h b/Libraries/LibJS/SourceTextModule.h
index 3b16d9543fa..765b562c14e 100644
--- a/Libraries/LibJS/SourceTextModule.h
+++ b/Libraries/LibJS/SourceTextModule.h
@@ -14,7 +14,7 @@
 namespace JS {
 
 // 16.2.1.6 Source Text Module Records, https://tc39.es/ecma262/#sec-source-text-module-records
-class SourceTextModule final : public CyclicModule {
+class JS_API SourceTextModule final : public CyclicModule {
     GC_CELL(SourceTextModule, CyclicModule);
     GC_DECLARE_ALLOCATOR(SourceTextModule);
 
diff --git a/Libraries/LibJS/SyntaxHighlighter.h b/Libraries/LibJS/SyntaxHighlighter.h
index 5a4a2b2d5f7..632e6cbcffb 100644
--- a/Libraries/LibJS/SyntaxHighlighter.h
+++ b/Libraries/LibJS/SyntaxHighlighter.h
@@ -6,11 +6,12 @@
 
 #pragma once
 
+#include <LibJS/Forward.h>
 #include <LibSyntax/Highlighter.h>
 
 namespace JS {
 
-class SyntaxHighlighter : public Syntax::Highlighter {
+class JS_API SyntaxHighlighter : public Syntax::Highlighter {
 public:
     SyntaxHighlighter() = default;
     virtual ~SyntaxHighlighter() override = default;
diff --git a/Libraries/LibJS/SyntheticModule.h b/Libraries/LibJS/SyntheticModule.h
index 64efe6ba7e0..3dfd561ea19 100644
--- a/Libraries/LibJS/SyntheticModule.h
+++ b/Libraries/LibJS/SyntheticModule.h
@@ -13,7 +13,7 @@
 namespace JS {
 
 // 16.2.1.8 Synthetic Module Records, https://tc39.es/ecma262/#sec-synthetic-module-records
-class SyntheticModule final : public Module {
+class JS_API SyntheticModule final : public Module {
     GC_CELL(SyntheticModule, Module);
     GC_DECLARE_ALLOCATOR(SyntheticModule);
 
@@ -39,6 +39,6 @@ private:
     EvaluationFunction m_evaluation_steps; // [[EvaluationSteps]]
 };
 
-ThrowCompletionOr<GC::Ref<Module>> parse_json_module(Realm& realm, StringView source_text, ByteString filename);
+JS_API ThrowCompletionOr<GC::Ref<Module>> parse_json_module(Realm& realm, StringView source_text, ByteString filename);
 
 }
diff --git a/Libraries/LibJS/Token.h b/Libraries/LibJS/Token.h
index 16789830970..fbc767c8fd1 100644
--- a/Libraries/LibJS/Token.h
+++ b/Libraries/LibJS/Token.h
@@ -10,6 +10,7 @@
 #include <AK/String.h>
 #include <AK/StringView.h>
 #include <AK/Variant.h>
+#include <LibJS/Export.h>
 
 namespace JS {
 
@@ -179,7 +180,7 @@ enum class TokenCategory {
     Identifier
 };
 
-class Token {
+class JS_API Token {
 public:
     Token() = default;