MRPack Validator — Check Your .mrpack for Errors

Before publishing or sharing a .mrpack, run it through this validator. It checks the manifest against the Modrinth spec, verifies every download URL is reachable, and recomputes each SHA-512 hash.

100% browser-sideNo uploadNo signupFree

Validate a .mrpack file

Drag & drop a .mrpack here to validate

or click to choose

Choose .mrpack

…

🗂 Batch mode: select multiple files to process them in one run.

How to Use This Tool

Three steps, about a minute. Everything runs inside your browser — the file never leaves your device.

Add your file

Drag a file onto the drop zone, or click to browse. Hold Ctrl/Cmd to select several files at once — batch mode converts them one after another.

Let it run

The manifest is read, every mod is fetched from its original source, and the progress bar reports each file as it completes.

Download the result

Your finished file downloads automatically. Use the buttons in the result panel to save it again, or start over with a new upload.

Good to know

Nothing is uploaded to a server. The file is read with the browser File API and processed in memory.
Large modpacks (200+ mods) need a stable connection. If a download fails the file is skipped and listed in the result panel.
Every downloaded JAR is checked against the SHA-512 hash recorded in the manifest, so a corrupt download is caught before it is packed.
The tool works on mobile browsers, but a desktop connection is much faster for packs over 100 MB.

What it checks

Schema compliance

formatVersion is set and is supported
game equals "minecraft"
versionId and name present
dependencies includes Minecraft and a supported loader

Files array

Each files[] entry has a path, at least one downloads URL, and SHA-512 hash
Paths do not contain .. traversal
Paths target only allowed folders (mods/, config/, resourcepacks/, etc.)

URL reachability

Each download URL returns 200 OK
Domain is on Modrinth's allowed-host list (modrinth.com, github.com, gitlab.com)

Hash verification

SHA-512 of each fetched file matches the manifest declaration
File size matches the declared fileSize

Why validate?

An invalid .mrpack will fail to install on at least one launcher. Validation catches issues early so you do not publish a pack only to receive bug reports the next day.