Grim Anticheat
by GrimAC
Grim Anticheat is a server-side anticheat for the Fabric loader that also runs on Paper, Spigot, Bukkit, Purpur and Folia servers.
What it does
The anticheat checks player movement and actions on the server, and it is built to run asynchronously and across several threads so that checks do not block the main game loop. Its detection logic is predictive, judging a movement against what the client could plausibly have done rather than only against fixed limits. The project covers game versions 1.16.1 – 1.21.1 as its main target, with builds listed across the wider catalog range.
Fabric API is required and must be installed next to the anticheat. Grim Anticheat is open source under the GNU General Public License v3.0 or later, and the source code, issue tracker and wiki are public. Snapshot builds are not listed for this mod. Files are published for 83 release versions, 1.7.2 – 26.2, and the latest Fabric file is 2.3.74-3a9cdf1 for 26.2, released on 2026-10-15 on the alpha channel.
Key features
Asynchronous checks
Checks run asynchronously on multiple threads, keeping the server tick loop free of anticheat work.
Predictive movement detection
Movement is compared with a prediction of what the client could legitimately do, not only with fixed thresholds.
Geyser player exemption
Bedrock players connecting through Geyser can be fully exempt when the backend server is set up for that purpose.
Client version awareness
Checks account for the client version on the server, since movement depends on it.
Public documentation
A wiki with examples, an issue tracker and a separate API repository are published for server owners and developers.
Compatibility
Latest build for each game version and loader.
26.x4 of 4 versions with builds
1.21.x12 of 12 versions with builds
1.20.x7 of 7 versions with builds
1.19.x5 of 5 versions with builds
1.18.x3 of 3 versions with builds
1.17.x2 of 2 versions with builds
1.16.x5 of 5 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Protecting survival servers
Server owners running survival or multiplayer worlds on Paper, Spigot or Folia can use the anticheat to flag movement and combat cheats.
Mixed-client networks
Networks that accept Bedrock players through Geyser and Java players on several versions can rely on the Geyser exemption and client version handling.
Who it’s for: Server owners and administrators who run Minecraft Java Edition servers on Paper, Spigot, Bukkit, Purpur or Folia and want an open source anticheat with public documentation.
Questions
Does Grim Anticheat need Fabric API?
Where should the Geyser setup sit for Bedrock players to be exempt?
Why does the client version matter for checks?
In the catalog
Grim Anticheat is one of 8,016 Management mods on ModsFinder, and one of 5,930 Management mods for Fabric. 13,894 mods support Minecraft 26.2.
Similar mods
What the author says
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. What makes Grim stand out against other anticheats?
Official listing
- Modrinth page
- modrinth.com/mod/grimac
- Owner
- GrimAC
- Published
- 2024-03-22
- Updated on Modrinth
- 2026-10-15
- Facts verified
- 2026-10-15