Open source · Browser-only · Zero servers

About Moddator

A completely free, serverless Minecraft mod and shader updater. Your files never leave your device. Not affiliated with Mojang or Microsoft.

Always Free

Moddator is and always will be free to use. We support development through non-intrusive ads. No paywalls, no accounts, no subscriptions.

Open Ecosystem

Built on the open Modrinth API. Modrinth hosts tens of thousands of mods and shaders, with new releases appearing automatically — no manual list updates needed.

Private by Design

Your mod and shader files are hashed locally in your browser using SHA-512. Only the hash — a 128-character fingerprint — is sent to Modrinth. Your actual files stay on your machine.

Browser-Only

There is no backend, no database, and no server of any kind. Everything — file reading, hashing, ZIP generation — runs entirely within your browser tab using IndexedDB and the Web Crypto API.

How It Works — Technically

When you upload your mods folder, Moddator reads each .jar file locally and computes a SHA-512 hash using your browser's built-in crypto.subtle.digest API. This hash is then sent to the Modrinth version file endpoint (GET /v2/version_file/{hash}) to identify the mod.

Once a mod is identified, Moddator fetches its full version list from Modrinth to determine which Minecraft versions and mod loaders it supports. You then pick your target version and Moddator downloads the appropriate updated .jar files directly from the Modrinth CDN. These files are assembled into a ZIP using JSZip — entirely in memory in your browser tab.

The final ZIP is presented to you as a download. Nothing is stored on our servers because there are no servers. Your file data is stored only in your browser's IndexedDB between steps of the same session and is cleared when you start a new upload.

Files are processed entirely in your browser. Nothing is uploaded to our servers.

Privacy

The only external network requests made by Moddator are to https://api.modrinth.com/v2 and https://cdn.modrinth.com. These requests contain only file hashes and are subject to Modrinth's privacy policy. We do not collect, log, or transmit any user data. Read our full Privacy Policy.

Limitations

Only mods and shaders published on Modrinth can be identified and updated. Mods from CurseForge, paid mods (like OptiFine), or unpublished mods will be flagged as "Not on Modrinth" and included in your ZIP at their current version unchanged.
Version availability depends entirely on what mod authors have published on Modrinth. If a mod author hasn't released a version for your chosen Minecraft version, Moddator can't create one.
Moddator does not handle mod dependencies — if a mod update requires a newer version of a library mod, you may need to update that separately.
Large packs (50+ mods) may hit Modrinth's public API rate limits. Adding a free Modrinth API key in the upload step significantly raises those limits.

Credits

Moddator was built using the Modrinth Open API, JSZip for in-browser ZIP generation, and the Web Crypto API for local SHA-512 hashing. No other frameworks or libraries are used. Not affiliated with Mojang Studios or Microsoft. Minecraft™ is a trademark of Mojang Studios.