Jester Anti Cheat

Jester Anti Cheat is a packet-based anti-cheat for Minecraft servers, built on the proven Grim prediction engine and focused on low false-positives — even across mixed client versions (1.8.9+ via ViaVersion / ViaBackwards) and behind BungeeCord / Velocity proxies.

✨ Highlights

• 160+ checks. Grim's movement-prediction core, plus 40+ checks that are not part of upstream Grim:
  • Combat — KillAura (A–D), Reach, TriggerBot, Criticals, Crystal/Anchor/Bed aura, Hitboxes
  • Auto-tools — AutoClicker, AutoTotem, AutoArmor, AutoPot, AutoEat, ChestStealer, InventoryWalk
  • World — Nuker, Tower, Scaffold, FastPlace, VeinMiner, PacketMine
• Per-check configuration. Every check has its own enabled, punishable, max-violations, alert and punishment settings.
• Tuned for real servers. Generous grace windows for proxy / version-translation jitter, ping, low-TPS dips and other common false-positive sources.
• Database logging (SQLite / MySQL) of violations, punishments and profiles.
• In-game tooling under /jester — alerts with hover info, violation history, freeze, spectate, stats and more.

🧩 Compatibility

• Platforms: Bukkit · Spigot · Paper · Purpur · Folia
• Server versions: same range as the Grim engine (api-version 1.13). Actively tested on 1.21.4 and 1.21.11.
• Client versions: 1.8.9+ are supported via ViaVersion on a modern server.

⚙️ Requirements

• PacketEvents — required. The plugin will not enable without it.
• ViaVersion + ViaBackwards (optional) — needed only if you want to protect players on client versions older than your server.

💬 Support

Questions, bug reports or setup help? Join our Discord: https://discord.gg/PfDDFKMaMs

📜 Credits & License

Jester Anti Cheat is built on the Grim anti-cheat engine (https://github.com/GrimAnticheat/Grim), which is licensed under GPL-3.0. Because of that, Jester Anti Cheat is itself released under GPL-3.0 — the complete source code is available here:

➡️ https://github.com/AmirAbbas8585/jester-anticheat

The branding, configuration, the 40+ extra checks listed above, and many false-positive and plugin-compatibility fixes are this project's own work, layered on top of the Grim engine.