A free, open-source Fabric anticheat that watches other players from your client — 36 read-only checks, lag-aware guards, cheater-tier nametag prefixes, and a full observer toolkit (/ius chathist, transcript, evidence, note, session, record). No server install, no outgoing packets, no telemetry.
v1.4 reworks the replay/clip pipeline and lands a detection-accuracy pass: clips save instantly, capture the world around the action as it happens, and the last two known false positives are gone. Still read-only, still client-sided.
A moderator suite for the whole loop: an instant replay of the scene, portable evidence clips, and player exemptions. It turns a raw detection into something you can review and act on, and it stays read-only and client-sided throughout.
Iustitia never sends a packet, cancels an event, or touches your own player. A single HEAD mixin observes incoming packets; every detection is inference over what the server already broadcast.
A client-sided anticheat that cries wolf is worse than none — you stop trusting the prefix. So Iustitia is tuned conservatively: 16 of 36 checks are primary definitive (an alert from one proves cheating), two more corroborate without ever marking a player on their own, and the remaining 18 are inferential. Tiers need cross-check corroboration to reach red.
No marketing percentages — just what the mod actually is.
Each links to a deep page — what it detects, the observer signature, false-positive guards, and configuration defaults.