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A repacking tool for Minecraft mods to optimize size and loading speed of mods.


MC-Repack was created with a simple thought in mind: How many Minecraft mods and resource packs come with unoptimized files? And I don't mean just pretty-printed JSON files. You will be surprised that in some cases a PNG file's metadata added by Photoshop is much larger than its content.

One other important thing is that MC-Repack determines if a file really needs to be compressed.Most PNG files and smaller JSON files will usually be stored uncompressed. This kind of operation saves bytes if a "compressed" form is larger than original. Also, uncompressed data can be loaded faster.

This is a great tool that can be helpful for:

MC-Repack shows all errors happened during repacking. Most of them are errors that can be simply ignored (like "trailing comma at line X column Y").


Original vs repacked

MC-Repack can save about 10% of file size for larger mods (see data below). It may be difficult to understand, but JAR files are already compressed. The difference of uncompressed files is usually much larger.

Check all tested mods HERE!


After installation, the tool can be run by just double-clicking its file. It can also be used by typing the mc-repack command in a terminal/shell.

When a file path is provided, then MC-Repack will repack the file contents into a file ending with _repack.jar. If a path is a directory, then all files inside (non-recursive) will be repacked.

More options are provided by typing mc-repack --help in a shell/terminal.

Try MC-Repack now