QuantumAC

QuantumAC

A lightweight, server-side anti-cheat plugin for PaperMC 1.21.1 – 1.21.11

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QuantumAC is a server-side anti-cheat plugin built specifically for PaperMC. It catches the most common cheats through a combination of movement analysis, packet inspection, and world-state occlusion — without relying on client-side modifications.

All detections happen on the server. There is nothing a cheat client can do about packets that were never sent, or a lagback it never saw coming.

Checks

- AntiScaffold — detects sustained upward or level movement in air. Lagbacks the player to their last safe ground position. - AntiScaffold — flags horizontal movement beyond vanilla limits, accounting for sprinting, speed potions, ice, soul sand, and post-knockback momentum. - AntiScaffold — detects unnatural attack patterns: inhuman attack rate, multi-target switching within a single swing window, and robotic aim angle consistency via packet analysis. - AntiScaffold — catches suppressed fall damage. Reapplies blocked damage and lagbacks on confirmed damage-free landings, with mace smash and wind-charge exemptions. - AntiScaffold — detects upward boat movement beyond vanilla physics. - AntiScaffold — flags critical hits landed while the player is grounded, blocking hit-consistent criticals cheats. - AntiScaffold — enforces minimum block break times relative to tool efficiency and block hardness. - AntiScaffold — server-side entity and block entity occlusion. Hidden entities and block entities are never sent to the client, so no ESP mod can reveal them. - AntiScaffold — detects players when they walk on water/lava and gives them warnings. - AntiScaffold — server side physics calculations for hacks such as AntiKnockback. - AntiScaffold — enforces physical packet integrity by blocking malformed rotation data (NaN), spoofed Y-coordinates used for MaceDMG and Freecam exploits, and impossible movement deltas beyond vanilla limits. - AntiScaffold — prevents air place and placing blocks without looking at the general direction.

Features

- Violation level system with configurable thresholds for alerts, kicks, and bans - Lagback on movement violations — no teleport spam, just a clean snap to last safe position - In-game GUI to toggle individual checks at runtime without reloading - Staff alerts with configurable violation threshold - Per-check configuration: enable/disable, thresholds, multipliers, and VL costs - `quantumac.bypass` permission for staff or trusted players

Requirements

- PaperMC 1.21.x - ProtocolLib 5.4.0 - packetevents 2.12.1

Commands

| Command | Description | |---|---| | `/quantumac checks` | Open the check toggle GUI | | `/quantumac reload` | Reload config | | `/quantumac alerts` | Toggle staff alerts for yourself | | `/quantumac violations <player>` | View a player's current violation levels |