Anti Chat Lag
by Itamio
Anti Chat Lag stops the client from trying to sign chat messages, which is the step that freezes the game when a player sends chat on an offline-mode server.
What it does
The freeze happens because the client keeps trying to generate a chat signature even when no valid authentication keys exist. Anti Chat Lag blocks the signing setup, so messages are sent right away without holding the game thread. Other chat behavior, including formatting and commands, keeps working as before.
The mod is client-side only, so the server does not need it. It is meant for offline-mode servers, which already accept unsigned messages. Online-mode servers, where Mojang authentication is in place, still get signed messages normally. The mod needs no configuration once installed, and it works alongside performance mods such as Sodium and Iris. The code is open source under the MIT License, and the release is 1.0.0 for 1.21.11, published on Fabric only.
Key features
Immediate message sending
Chat messages are sent at once instead of stalling the game while the client prepares a signature.
No configuration
Once installed, the fix is active from the start, with no options to set.
Other chat features intact
Formatting, commands and the rest of the chat system continue to function normally.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Offline-mode servers
Players who join servers that accept unsigned messages no longer lose time to the chat freeze.
Who it’s for: Players on Fabric who join offline-mode or cracked servers and want chat to stop freezing the game. Server owners do not need to install anything.
How it compares
ChatLagFix is also a client-side Fabric mod for 1.21.11 under the MIT License and open source, so it covers the same version and environment. MChat Fix is client-side for 1.21.11 as well, but it is published under All rights reserved and is not open source. Anti Snowballs targets 1.21 – 1.21.5 and does not cover 1.21.11.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Anti Chat Lag | Fabric | 1.21.11 | Client-side only | 2026-08-03 |
| ChatLagFix | Fabric | 1.21.11 | Client-side only | 2026-03-17 |
| MChat Fix | Fabric | 1.21.11 | Client-side only | 2026-06-10 |
| Anti Snowballs | Fabric | 1.21 – 1.21.5 | Client-side only | 2025-07-22 |
Questions
Does Anti Chat Lag need Fabric API?
Does the server need Anti Chat Lag installed?
Will the fix break chat on online-mode servers?
In the catalog
Anti Chat Lag is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 19,862 mods support Minecraft 1.21.11.
More from Itamio
Similar mods
What the author says
Anti Chat Lag eliminates the game freeze that occurs when sending chat messages on offline-mode (cracked) servers. It does this by preventing the client from attempting to generate a chat message signature, which is the root cause of the lag. This mod is client-side only. The server does not need it — offline-mode…
Official listing
- Modrinth page
- modrinth.com/mod/antichatlag
- Owner
- Itamio
- Published
- 2026-08-03
- Updated on Modrinth
- 2026-08-03
- Facts verified
- 2026-10-15