GrimAC

GrimAC is an free open source Minecraft anticheat designed to support the latest versions of Minecraft. It currently supports minecraft versions 1.8-1.21. Geyser players are fully exempt.

This project is considered feature-complete for the 2.0 (open-source) branch. If you would like a bug fix or enhancement and cannot sponsor the work, pull requests are welcome. A premium version is planned, which will offer additional subscription-based paid checks, such as heuristics.

Installation notes

- Java 17 is now required. More information here.

- Paper, Spigot, and Folia are currently supported.

- If you use Geyser, place Floodgate on the backend server so grim can exempt bedrock players. Grim cannot access the Floodgate API if it is on the proxy.

- If you use ViaVersion, it should be on the backend server as movement is highly dependent on client version.

Support & wiki information

- Support & discussion: Discord

- Report issues: Issues

- Wiki & examples: Wiki

Developer API

Grim's API allows you to integrate Grim into your own plugins.

- API repository: GrimAPI

- Wiki info: Wiki

How to compile

1. git clone https://github.com/GrimAnticheat/Grim.git

2. cd Grim

3. ./gradlew build

4. The final jar will compile into the build/libs folder

Grim supremacy

What makes Grim stand out against other anticheats?

Movement Simulation Engine

We have a 1:1 replication of the player's possible movements

This covers everything from basic walking, swimming, knockback, cobwebs, to bubble columns

It even covers riding entities from boats to pigs to striders

Built upon covering edge cases to confirm accuracy

1.13+ clients on 1.13+ servers, 1.12- clients on 1.13+ servers, 1.13+ clients on 1.12- servers, and 1.12- clients on 1.12- servers are all supported regardless of the large technical changes between these versions.

The order of collisions depends on the client version and is correct

Accounts for minor bounding box differences between versions, for example:

Single glass panes will be a + shape for 1.7-1.8 players and for 1.9+ players

1.13+ clients on 1.8 servers see the + glass pane hitbox due to ViaVersion

Many other blocks have this extreme attention to detail.

Waterlogged blocks do not exist for 1.12 or below players

Blocks that do not exist in the client's version use ViaVersion's replacement block

Block data that cannot be translated…