A simple to install plugin that gives a separate chat room to each world. Users in one world will not see the chat messages of users in other worlds.
Users automatically switch rooms when they travel to a different world.
The plugin requires no configuration and has no commands.
Note that this project requires the plugin Multiverse-Core.
Released under GPLv2: https://github.com/rocky1138/EachWorldHasItsOwnChat
I like pancakes.