Anti-Cheat Plugins
Hack detection, prevention and player monitoring.
Matrix AntiCheat
PremiumServer-side anti-cheat with advanced detection for fly, speed, kill-aura, X-ray and many more cheat types.
Grim Anticheat
Prediction-based anti-cheat. Simulates player movement server-side and compares it with client packets for accurate cheat detection.
Spartan AntiCheat
PremiumAnti-cheat with 30+ checks covering combat, movement and world interactions. Includes a cloud-based detection learning system.
Free or paid
Grim is free and open source. It simulates the movement a vanilla client would make and compares it with what the player sends, and it supports Minecraft 1.8 through 26.2; its README recommends downloading it from Modrinth. Matrix and Spartan are paid plugins with their own sets of checks, and Matrix also needs ProtocolLib.
Start with alerts, not bans
Lag can look like cheating to any anti-cheat. Run it with alerts only for the first week and read what it flags before you let it punish anyone. In Grim, staff with grim.alerts switch alerts on and off with /grim alerts. Tune the thresholds after that, one check at a time.
Bedrock players and proxies
Bedrock players who join through Geyser move differently from Java clients. Grim exempts them completely to avoid false flags, and when Geyser runs on a proxy, Floodgate must also be on the backend server where Grim runs. ViaVersion belongs on the backend only; Grim does not support it on the proxy, not even when it is on the backend too. Grim itself needs Java 17 or newer.