BasaltNeo — Server Integrity Client

BasaltNeo is the client-side component of a two-part mod integrity system built for NeoForge 1.21.1 server owners who want to keep their modpacks clean.

When you join a server running BasaltNeo, it verifies that your mods and resource packs match the server's approved list. That's it. No invasive scans, no background processes when you're not on a server, it sits completely dormant until you connect somewhere that uses it.

What it checks

Every .jar in your mods/ folder
Every .zip in your resourcepacks/ folder

Nothing outside your game directory is ever touched.

How it works
Each file gets a SHA-256 fingerprint that gets checked against the server's allowlist on connect. If something doesn't match, the server handles it from there. File changes mid-session are detected instantly rather than on a timer, so there's no window to swap things out while you're already in.

For server owners
This mod is meant to be bundled in your modpack. The server-side counterpart (BasaltNeo Server) is where you manage your allowlist, configure enforcement, and view logs. Players just need this in their mods folder and no configuration is required on their end. Please reach out to me on discord @ officialmrbasalt for setup help.

A notice is shown in chat when you join a server using BasaltNeo, letting you know what's being checked and why.

Basalt Neo