The .enzpack modpack format

What is in an .enzpack#

• The pack's details: name, version, summary, icon, Minecraft version, loader and a suggested amount of memory.
• References to every mod, resource pack, shader pack and data pack that is on Modrinth or CurseForge. A reference is the project, the exact file and its hash, not the file itself. The launcher downloads those files from Modrinth or CurseForge when you import the pack.
• Your own files: configs, scripts (KubeJS and others), options and any custom jar you ticked. Identical files are stored once, and all of them are compressed together.

Logs, crash reports, caches and other files the game creates again are never put into a pack.

How small is it?#

Real packs exported with Enzonic Launcher, the same files in each format:

An .enzpack is smaller because a .mrpack can only link to Modrinth: mods that are only on CurseForge go inside the file. A .enzpack links to both, and compresses all configs in one stream instead of one by one.

Is it safe?#

• Every downloaded mod must match the hash written in the pack. If Modrinth or CurseForge no longer has that exact file, the import stops and nothing is installed.
• The whole file has a checksum, and every stored file has its own. A damaged or edited pack is refused.
• Paths are checked so a pack can only write inside its new instance, and files that would unpack to an unreasonable size are refused.
• Nothing in a pack is ever run.
• Some CurseForge authors do not allow downloads from other apps. For those files the launcher shows the same manual download step as for CurseForge modpacks: you download them from curseforge.com and the launcher checks each one.

How to use it#

• Export: open an instance's menu and choose Export .enzpack…, or use Modpacks › Create. .enzpack is the default; .mrpack and the CurseForge zip are still there. After the export the launcher shows the file size and what the same pack would weigh as a .mrpack.
• Import: drop the file anywhere on the launcher window, or choose it in Modpacks › Import.
• Share: upload the .enzpack in Modpacks › Share to get a share code and a link. Friends paste the code into their launcher.

You need Enzonic Launcher to install an .enzpack. To use a pack in another launcher, export it as .mrpack or as a CurseForge zip instead.

For developers#

File type .enzpack, media type application/vnd.enzonic.pack. A file starts with the bytes 89 45 4E 5A 50 41 43 4B and a format version, followed by one LZMA2 stream (a JSON file list, then the stored files) and a SHA-256 checksum. Newer launchers can add optional data that older ones ignore; a pack that needs a newer launcher says so instead of installing half. The share API accepts .enzpack uploads, see the API reference.