Minecraft Mod Checker (Java)
Drop your mods folder and see every mod's name, version and loader, plus the problems that stop a modpack from starting: duplicates, missing dependencies, wrong versions, mods for another Minecraft version and Fabric/Forge mixes.
Runs on your device · nothing uploaded
This tool is code that runs inside your browser. Your files, text and pictures are read here and never sent to a server, so it even works offline once loaded. Signed in? Only what you save to your account (My Kit, wardrobe) or publish is uploaded.
Drop your mods folder here
Works with Fabric, Quilt, Forge and NeoForge. Mods are read on your device and never uploaded.
EXAMPLEThese are made-up mods with three common problems. Drop your own mods folder to check yours.
Type your Minecraft version to check compatibility.
3 problems in 5 mods
- Duplicate
Cave Maps is installed 2 times
Keep one file and delete the others: cave-maps-1.0.jar (1.0.0), cave-maps-1.1.jar (1.1.0).
- Wrong version
Better Torches needs a different version of Lib Core
It needs >=2.0.0, but 1.4.0 is installed.
- Missing
Quick Stack needs “inventorylib”
Install inventorylib.
| Mod | Version | Loader | Minecraft |
|---|---|---|---|
| Better Torchesbetter-torches-3.2.jar | 3.2.0 | Fabric | any |
| Cave Mapscave-maps-1.0.jar | 1.0.0 | Fabric | any |
| Cave Mapscave-maps-1.1.jar | 1.1.0 | Fabric | any |
| Lib Corelib-core-1.4.0.jar | 1.4.0 | Fabric | any |
| Quick Stackquick-stack-2.0.jar | 2.0.0 | Fabric | any |
.
Problems it finds
| Problem | What it means |
|---|---|
| Duplicate | The same mod is in the folder twice (often an old and a new version) |
| Missing | A mod needs another mod that isn't installed |
| Wrong version | A required mod is installed, but not a version the other mod accepts |
| Wrong Minecraft | A mod is built for a different Minecraft version |
| Loader mix | Fabric and Forge mods in the same folder (a game uses one loader) |
| Unreadable | A file is broken or isn't a mod |
How to use it
- Open your mods folder (in .minecraft, or your launcher instance's folder).
- Drag the whole folder onto the box, or choose the .jar files.
- Check the Minecraft version (it's guessed from your mods) and read the problems list.
- Fix the problems from the top, then start the game. Use Copy mod list to share your pack.
How it works
Mods are .jar files, which are ZIP archives. The tool opens each one in your browser and reads its info file: fabric.mod.json, quilt.mod.json, or META-INF/mods.toml for Forge and NeoForge. It also reads mods bundled inside other mods, like Fabric API's modules, so they are not reported as missing. Then it checks every requirement against what is installed.
Questions
Why won't my modpack start?
The most common reasons are a missing library mod (like Fabric API or GeckoLib), a mod for a different Minecraft version, or the same mod installed twice. This tool finds all three.
Are my mods uploaded?
No. Everything is read in your browser. Nothing leaves your computer.
My game still crashes: what next?
Drop your crash report into the Crash Doctor. It reads the error itself and often names the exact mod.
Related tools
By PickaxeKit Editorial Team. Updated 2026-11-09.