diff --git a/Userland/Libraries/LibGfx/CMakeLists.txt b/Userland/Libraries/LibGfx/CMakeLists.txt
index 2a6d9750db5..59c9a7fd0f8 100644
--- a/Userland/Libraries/LibGfx/CMakeLists.txt
+++ b/Userland/Libraries/LibGfx/CMakeLists.txt
@@ -22,6 +22,7 @@ set(SOURCES
     PBMLoader.cpp
     PGMLoader.cpp
     PNGLoader.cpp
+    PNGWriter.cpp
     PPMLoader.cpp
     Point.cpp
     Rect.cpp
diff --git a/Userland/Libraries/LibGfx/PNGWriter.cpp b/Userland/Libraries/LibGfx/PNGWriter.cpp
new file mode 100644
index 00000000000..99fe188e4f9
--- /dev/null
+++ b/Userland/Libraries/LibGfx/PNGWriter.cpp
@@ -0,0 +1,228 @@
+/*
+ * Copyright (c) 2021, Pierre Hoffmeister
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "PNGWriter.h"
+#include <AK/String.h>
+#include <LibCrypto/Checksum/CRC32.h>
+
+namespace Gfx {
+
+class PNGChunk {
+public:
+    PNGChunk(const String&);
+    const Vector<u8>& data() const { return m_data; };
+    const String& type() const { return m_type; };
+    void add_u8(u8);
+    void add_u16_big(u16);
+    void add_u32_big(u32);
+    void add_u16_little(u16);
+    void add_u32_little(u32);
+
+private:
+    Vector<u8> m_data;
+    String m_type;
+};
+
+class NonCompressibleBlock {
+public:
+    void finalize(PNGChunk&);
+    void add_byte_to_block(u8 data, PNGChunk&);
+
+    u32 adler_s1() { return m_adler_s1; }
+    u32 adler_s2() { return m_adler_s2; }
+
+private:
+    void add_block_to_chunk(PNGChunk&, bool);
+    void update_adler(u8);
+    bool full() { return m_non_compressible_data.size() == 65535; }
+    Vector<u8> m_non_compressible_data;
+    u32 m_adler_s1 { 1 };
+    u32 m_adler_s2 { 0 };
+};
+
+PNGChunk::PNGChunk(const String& type)
+    : m_type(move(type))
+{
+}
+
+void PNGChunk::add_u8(u8 data)
+{
+    m_data.append(data);
+}
+
+void PNGChunk::add_u16_little(u16 data)
+{
+    m_data.append(data & 0xff);
+    m_data.append((data >> 8) & 0xff);
+}
+
+void PNGChunk::add_u32_little(u32 data)
+{
+    m_data.append(data & 0xff);
+    m_data.append((data >> 8) & 0xff);
+    m_data.append((data >> 16) & 0xff);
+    m_data.append((data >> 24) & 0xff);
+}
+
+void PNGChunk::add_u32_big(u32 data)
+{
+    m_data.append((data >> 24) & 0xff);
+    m_data.append((data >> 16) & 0xff);
+    m_data.append((data >> 8) & 0xff);
+    m_data.append(data & 0xff);
+}
+
+void PNGChunk::add_u16_big(u16 data)
+{
+    m_data.append((data >> 8) & 0xff);
+    m_data.append(data & 0xff);
+}
+
+void NonCompressibleBlock::add_byte_to_block(u8 data, PNGChunk& chunk)
+{
+    m_non_compressible_data.append(data);
+    update_adler(data);
+    if (full()) {
+        add_block_to_chunk(chunk, false);
+        m_non_compressible_data.clear();
+    }
+}
+
+void NonCompressibleBlock::add_block_to_chunk(PNGChunk& png_chunk, bool last)
+{
+    if (last) {
+        png_chunk.add_u8(1);
+    } else {
+        png_chunk.add_u8(0);
+    }
+
+    auto len = m_non_compressible_data.size();
+    auto nlen = ~len;
+
+    png_chunk.add_u16_little(len);
+    png_chunk.add_u16_little(nlen);
+
+    for (auto non_compressed_byte : m_non_compressible_data) {
+        png_chunk.add_u8(non_compressed_byte);
+    }
+}
+
+void NonCompressibleBlock::finalize(PNGChunk& chunk)
+{
+    add_block_to_chunk(chunk, true);
+}
+
+void NonCompressibleBlock::update_adler(u8 data)
+{
+    m_adler_s1 = (m_adler_s1 + data) % 65521;
+    m_adler_s2 = (m_adler_s2 + m_adler_s1) % 65521;
+}
+
+void PNGWriter::add_chunk(const PNGChunk& png_chunk)
+{
+    Vector<u8> combined;
+    for (auto character : png_chunk.type()) {
+        combined.append(character);
+    }
+    combined.append(png_chunk.data());
+
+    auto crc = BigEndian(Crypto::Checksum::CRC32({ (const u8*)combined.data(), combined.size() }).digest());
+    auto data_len = BigEndian(png_chunk.data().size());
+
+    ByteBuffer buf;
+    buf.append(&data_len, sizeof(u32));
+    buf.append(combined.data(), combined.size());
+    buf.append(&crc, sizeof(u32));
+
+    m_data.append(buf.data(), buf.size());
+}
+
+void PNGWriter::add_png_header()
+{
+    const u8 png_header[8] = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
+    m_data.append(png_header, sizeof(png_header));
+}
+
+void PNGWriter::add_IHDR_chunk(u32 width, u32 height, u8 bit_depth, u8 color_type, u8 compression_method, u8 filter_method, u8 interlace_method)
+{
+    PNGChunk png_chunk { "IHDR" };
+    png_chunk.add_u32_big(width);
+    png_chunk.add_u32_big(height);
+    png_chunk.add_u8(bit_depth);
+    png_chunk.add_u8(color_type);
+    png_chunk.add_u8(compression_method);
+    png_chunk.add_u8(filter_method);
+    png_chunk.add_u8(interlace_method);
+    add_chunk(png_chunk);
+}
+
+void PNGWriter::add_IEND_chunk()
+{
+    PNGChunk png_chunk { "IEND" };
+    add_chunk(png_chunk);
+}
+
+void PNGWriter::add_IDAT_chunk(const RefPtr<Bitmap> bitmap)
+{
+    PNGChunk png_chunk { "IDAT" };
+
+    u16 CMF_FLG = 0x81d;
+    png_chunk.add_u16_big(CMF_FLG);
+
+    NonCompressibleBlock non_compressible_block;
+
+    for (int y = 0; y < bitmap->height(); ++y) {
+        non_compressible_block.add_byte_to_block(0, png_chunk);
+
+        for (int x = 0; x < bitmap->width(); ++x) {
+            auto pixel = bitmap->get_pixel(x, y);
+            non_compressible_block.add_byte_to_block(pixel.red(), png_chunk);
+            non_compressible_block.add_byte_to_block(pixel.green(), png_chunk);
+            non_compressible_block.add_byte_to_block(pixel.blue(), png_chunk);
+            non_compressible_block.add_byte_to_block(pixel.alpha(), png_chunk);
+        }
+    }
+    non_compressible_block.finalize(png_chunk);
+
+    png_chunk.add_u16_big(non_compressible_block.adler_s2());
+    png_chunk.add_u16_big(non_compressible_block.adler_s1());
+
+    add_chunk(png_chunk);
+}
+
+ByteBuffer PNGWriter::write(const RefPtr<Bitmap> bitmap)
+{
+    add_png_header();
+    add_IHDR_chunk(bitmap->width(), bitmap->height(), 8, 6, 0, 0, 0);
+    add_IDAT_chunk(bitmap);
+    add_IEND_chunk();
+
+    ByteBuffer buf;
+    buf.append(m_data.data(), m_data.size());
+    return buf;
+}
+
+}
diff --git a/Userland/Libraries/LibGfx/PNGWriter.h b/Userland/Libraries/LibGfx/PNGWriter.h
new file mode 100644
index 00000000000..d07ed9d273a
--- /dev/null
+++ b/Userland/Libraries/LibGfx/PNGWriter.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2021, Pierre Hoffmeister
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <LibGfx/Bitmap.h>
+
+namespace Gfx {
+
+class PNGChunk;
+
+class PNGWriter {
+public:
+    ByteBuffer write(const RefPtr<Bitmap>);
+
+private:
+    Vector<u8> m_data;
+    void add_chunk(const PNGChunk&);
+    void add_png_header();
+    void add_IHDR_chunk(u32 width, u32 height, u8 bit_depth, u8 color_type, u8 compression_method, u8 filter_method, u8 interlace_method);
+    void add_IDAT_chunk(const RefPtr<Bitmap>);
+    void add_IEND_chunk();
+};
+
+}