TabbyChat 2 is the successor to TabbyChat, which was originally created by RocketMan10404. The mod is mostly stable, but there may still be some bugs. Report any you find.
Stable builds are available on the Minecraft Forums topic and CurseForge, linked below.
TabbyChat 2 also has an API. Check the mnm.mods.tabbychat.api package for the source references.
Requires LiteLoader
After installing LiteLoader, copy TabbyChat-2 into your .minecraft/mods folder. Don't extract it.
If you wish to use forge on 1.10.x, the minimum version supported is build 2020. A bug was fixed in that version which was causing a crash with mixins (See #57).