What Is an .mrpack File? Modrinth's Modpack Format Explained

You downloaded a modpack from Modrinth and got a file ending in .mrpack. Your launcher doesn't recognize it, and double-clicking does nothing useful. So what is this format, and how do you actually use it?

The short answer

An .mrpack is Modrinth's modpack format. Under the hood it's just a ZIP archive with a specific structure — but instead of containing the mod JARs directly, it contains a manifest that lists each mod by download URL.

What's inside an .mrpack

If you rename an .mrpack to .zip and open it, you'll find:

• modrinth.index.json — the manifest. It lists every file the pack needs, each with a download URL, file size, and hash, plus the Minecraft and mod loader versions the pack targets.
• overrides/ — a folder of config files, resource packs, and other loose files that get copied into the game directory as-is.

That's it. The actual mod JARs are not in the file.

Why a manifest instead of the mods themselves?

Two reasons:

• Size. A manifest is a few kilobytes. Bundling hundreds of megabytes of mod JARs would make packs huge and slow to share.
• Licensing. Many mods don't allow redistribution. Linking to the official download respects the mod author's hosting and license.

The trade-off: before you can play, something has to read that manifest and actually download each mod.

How do you open or use an .mrpack?

You have two main options:

• A compatible launcher (like the Modrinth App or Prism Launcher) can import an .mrpack directly — it reads the manifest and downloads the mods for you.
• Convert it to a plain .zip with every mod already bundled, so it works with launchers and manual installs that don't speak .mrpack. That's exactly what this site does, right in your browser. See the step-by-step guide: How to Convert an .mrpack to a .zip.

Quick FAQ

Is an .mrpack just a renamed .zip? Structurally it's a ZIP, but renaming it won't give you a usable modpack — the mods still need to be downloaded from the manifest.

Can I edit an .mrpack? Yes — unzip it, change the overrides/ files or the modrinth.index.json manifest, and zip it back up. But for most people, converting to a ready-to-use .zip is simpler.