Sky AntiCheat

Sky Anti-Cheat

A lightweight, configurable anti-cheat for Paper servers on Minecraft 1.21.x and 26.x.

Sky Anti-Cheat detects the most common hacked-client cheats, cancels the illegal action, alerts your staff in real time, and punishes repeat offenders automatically.

Features

Movement

• Fly: vertical boosts, hovering and gliding
• Speed: ground and air speed, with potion, ice and walk-speed awareness
• NoFall: spoofed on-ground packets
• Jesus: walking on water
• Timer: game-speed manipulation, with lag compensation

Combat

• Reach: attacks from beyond legitimate range
• KillAura: hits outside the target's hitbox and multi-target hits
• AutoClicker: excessive CPS and robotic, perfectly even click patterns

World

• Xray: tracks rare-ore to stone ratios over a configurable time window
• Nuker: breaking too many blocks per second, or from too far away
• Scaffold: blocks placed where the player is not looking

Anti-ESP

Players behind solid blocks are hidden from other players' clients. Wallhacks, ESP boxes and tracers have nothing to render.
Staff with the bypass permission can still see everyone.

Staff tools

• Live, colored alerts for staff, plus console logging
• Violation levels (VL) that decay over time
• Automatic punishment: kick or run any console command (ban, tempban and so on)
• Per-check enable switch, max VL and setback behaviour
• Full hex color support in every message and the prefix

Commands

Command · Description
/skyac help · Show all commands
/skyac alerts · Toggle your cheat alerts
/skyac info · View a player's violations
/skyac reset · Clear a player's violations
/skyac status · Plugin status
/skyac reload · Reload the config

Aliases: /sac, /sky

Permissions

Permission · Description · Default
sky.ac.admin · Use admin commands · OP
sky.ac.alerts · Receive cheat alerts · OP
sky.ac.bypass · Bypass all checks · Nobody

Installation

1. Download the jar and drop it into your plugins folder.
2. Restart the server.
3. Edit plugins/SkyAntiCheat/config.yml to fit your server.

Requirements: Paper (or a Paper fork such as Purpur) on 1.21.x or 26.x. Java 21 for 1.21.x, Java 25 for 26.x. Spigot and CraftBukkit are not supported.

Recommended: enable Paper's anti-xray too

Sky Anti-Cheat detects xray by ore statistics, which catches cheaters after the fact. For the strongest protection, also enable Paper's built-in anti-xray (engine-mode: 2) in config/paper-world-defaults.yml, so xray clients see nothing useful in the first place.

Tuning and false flags

Every threshold is in config.yml. If legitimate players get flagged (high latency, plugins that move players, modded clients), raise the tolerance or buffer values for that check, or give the player sky.ac.bypass.

Please note

No server-side anti-cheat can stop every cheat. Sky Anti-Cheat targets the common ones, and its detections are heuristic, so test it on your server before relying on it.

Support

Found a bug or false flag? Open an issue on the issue tracker with your server version, the check name and the alert message.