This mod adds Twitch Chat to Minecraft. You can use it to keep track of chat while playing or just make your viewers feel special by having them appear in Minecraft Chat.

For 1.16.2, there is now a slim version available that comes without the advanced Chat Tweaks functionality (badges and emotes, high configurability) but can be used as a stopgap until Chat Tweaks is ready. Use the /twitch command ingame to get started.