diff --git a/launcher/CMakeLists.txt b/launcher/CMakeLists.txt
index b5ce4dabb..28bf407d4 100644
--- a/launcher/CMakeLists.txt
+++ b/launcher/CMakeLists.txt
@@ -95,6 +95,10 @@ set(CORE_SOURCES
     MMCTime.cpp
 
     MTPixmapCache.h
+
+    # Manifest.mf parser
+    Manifest.h
+    Manifest.cpp
 )
 if (UNIX AND NOT CYGWIN AND NOT APPLE)
 set(CORE_SOURCES
diff --git a/launcher/Manifest.cpp b/launcher/Manifest.cpp
new file mode 100644
index 000000000..7755d4b75
--- /dev/null
+++ b/launcher/Manifest.cpp
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Fjord Launcher - Minecraft Launcher
+ *  Copyright (C) 2024 Evan Goode <mail@evangoo.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This file incorporates work from OpenJDK, covered by the following copyright and
+ * permission notice:
+ *
+ *         Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
+ *         DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ *         This code is free software; you can redistribute it and/or modify it
+ *         under the terms of the GNU General Public License version 2 only, as
+ *         published by the Free Software Foundation.  Oracle designates this
+ *         particular file as subject to the "Classpath" exception as provided
+ *         by Oracle in the LICENSE file that accompanied this code.
+ *
+ *         This code is distributed in the hope that it will be useful, but WITHOUT
+ *         ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *         FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *         version 2 for more details (a copy is included in the LICENSE file that
+ *         accompanied this code).
+ *
+ *         You should have received a copy of the GNU General Public License version
+ *         2 along with this work; if not, write to the Free Software Foundation,
+ *         Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ *         Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ *         or visit www.oracle.com if you need additional information or have any
+ *         questions.
+ *
+ * The GNU General Public License version 2 is available at https://www.gnu.org/licenses/old-licenses/gpl-2.0.html.
+ */
+
+#include <string.h>
+#include <iostream>
+
+#include "Manifest.h"
+
+// Manifest specification:
+// https://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Manifest_Specification
+
+// The implementation of the Manifest class was ported to C++ from OpenJDK:
+// https://github.com/openjdk/jdk/blob/0584af23255b6b8f49190eaf2618f3bcc299adfe/src/java.base/share/classes/java/util/jar/Manifest.java#L274
+
+Manifest::Manifest(std::istream& is)
+{
+    read(is, std::nullopt);
+}
+
+bool Manifest::isValidName(const std::string& name)
+{
+    const auto len = name.length();
+    return 0 < len && len <= 70;
+}
+
+std::string Manifest::getErrorPosition(const std::optional<std::string>& filename, int line_number)
+{
+    if (!filename.has_value()) {
+        return "line " + std::to_string(line_number);
+    }
+    return "manifest of " + *filename + ":" + std::to_string(line_number);
+}
+
+int Manifest::readAttributes(section_t& section, std::istream& is, lbuf_t lbuf, const std::optional<std::string>& filename, int line_number)
+{
+    std::optional<std::string> name;
+    std::string value;
+
+    std::string full_line;
+
+    while (!is.eof() && is.getline(lbuf, MAX_LINE_LENGTH)) {
+        std::size_t len = strlen(lbuf);
+
+        line_number += 1;
+
+        if (is.fail()) {
+            throw std::length_error("line too long (" + getErrorPosition(filename, line_number) + ")");
+        }
+        if (len > 0 && lbuf[len - 1] == '\r') {
+            len -= 1;
+        }
+        if (len == 0) {
+            break;
+        }
+        std::size_t i = 0;
+        if (lbuf[0] == ' ') {
+            // continuation of previous line
+            if (!name.has_value()) {
+                throw std::runtime_error("misplaced continuation line (" + getErrorPosition(filename, line_number) + ")");
+            }
+            full_line.append(lbuf + 1, len - 1);
+
+            if (is.peek() == ' ') {
+                continue;
+            }
+            value = full_line;
+            full_line.clear();
+        } else {
+            while (lbuf[i++] != ':') {
+                if (i >= len) {
+                    throw std::runtime_error("invalid header field (" + getErrorPosition(filename, line_number) + ")");
+                }
+            }
+            if (lbuf[i++] != ' ') {
+                throw std::runtime_error("invalid header field (" + getErrorPosition(filename, line_number) + ")");
+            }
+            name = std::string{ lbuf, i - 2 };
+            if (is.peek() == ' ') {
+                full_line.clear();
+                full_line.append(lbuf + i, len - i);
+                continue;
+            }
+            value = std::string{ lbuf + i, len - i };
+        }
+        if (!isValidName(*name)) {
+            throw std::runtime_error("invalid header field name (" + getErrorPosition(filename, line_number) + ")");
+        }
+        section[*name] = value;
+    }
+    return line_number;
+}
+
+std::optional<std::string> Manifest::parseName(lbuf_t lbuf, std::size_t len)
+{
+    if (tolower(lbuf[0]) == 'n' && tolower(lbuf[1]) && tolower(lbuf[2]) == 'm' && tolower(lbuf[3]) && lbuf[4] == ':' && lbuf[5] == ' ') {
+        return std::string{ lbuf, 6, len - 6 };
+    }
+    return std::nullopt;
+}
+
+void Manifest::read(std::istream& is, const std::optional<std::string>& jar_filename)
+{
+    // Line buffer
+    char lbuf[MAX_LINE_LENGTH];
+    // Read the main attributes for the manifest
+    int line_number = readAttributes(m_main_section, is, lbuf, jar_filename, 0);
+
+    std::optional<std::string> name;
+
+    bool skip_empty_lines = true;
+    std::optional<std::string> lastline;
+
+    while (!is.eof() && is.getline(lbuf, MAX_LINE_LENGTH)) {
+        std::size_t len = strlen(lbuf);
+
+        line_number += 1;
+
+        if (is.fail()) {
+            throw std::length_error("manifest line too long (" + getErrorPosition(jar_filename, line_number) + ")");
+        }
+        if (len > 0 && lbuf[len - 1] == '\r') {
+            len -= 1;
+        }
+        if (len == 0 && skip_empty_lines) {
+            continue;
+        }
+        skip_empty_lines = false;
+
+        if (!name.has_value()) {
+            name = parseName(lbuf, len);
+            if (!name.has_value()) {
+                throw std::runtime_error("invalid manifest format (" + getErrorPosition(jar_filename, line_number) + ")");
+            }
+            if (is.peek() == ' ') {
+                // name is wrapped
+                lastline = std::string{ lbuf + 6, len - 6 };
+                continue;
+            }
+        } else {
+            // continuation line
+            std::string buf{ *lastline };
+            buf.append(lbuf + 1, len - 1);
+            if (is.peek() == ' ') {
+                // name is wrapped
+                lastline = buf;
+                continue;
+            }
+            name = buf;
+            lastline = std::nullopt;
+        }
+
+        section_t& attr = m_individual_sections[*name];
+        line_number = readAttributes(attr, is, lbuf, jar_filename, line_number);
+
+        name = std::nullopt;
+        skip_empty_lines = true;
+    }
+}
diff --git a/launcher/Manifest.h b/launcher/Manifest.h
new file mode 100644
index 000000000..1b668d060
--- /dev/null
+++ b/launcher/Manifest.h
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Fjord Launcher - Minecraft Launcher
+ *  Copyright (C) 2024 Evan Goode <mail@evangoo.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <map>
+#include <optional>
+#include <string>
+
+constexpr const int MAX_LINE_LENGTH = 512;
+using lbuf_t = char[MAX_LINE_LENGTH];
+
+using section_t = std::map<std::string, std::string>;
+using sections_t = std::map<std::string, section_t>;
+using manifest_t = std::pair<section_t, sections_t>;
+
+class Manifest {
+   public:
+    Manifest(std::istream& is);
+    section_t& getMainAttributes() { return m_main_section; }
+    sections_t& getEntries() { return m_individual_sections; }
+    section_t& getAttributes(std::string& name) { return m_individual_sections.at(name); }
+
+   private:
+    static std::string getErrorPosition(const std::optional<std::string>& filename, int line_number);
+    static std::optional<std::string> parseName(lbuf_t lbuf, std::size_t len);
+    static bool isValidName(const std::string& name);
+    int readAttributes(section_t& section, std::istream& is, lbuf_t lbuf, const std::optional<std::string>& jar_filename, int line_number);
+    void read(std::istream& is, const std::optional<std::string>& jar_filename);
+    section_t m_main_section;
+    sections_t m_individual_sections;
+};