AutoMod

AutoMod is Twitch's built-in filter. Messages get scored against categories such as discrimination, sexual content, hostility and profanity, at a strictness level the channel sets, and anything over the line goes into a queue where a moderator approves or denies it. Nothing is deleted automatically; the message simply never appears unless somebody lets it through. YouTube runs an equivalent under a different name, holding potentially inappropriate comments and chat messages for review. Both work best with a moderator actually watching the queue during a stream, since held messages nobody clears just vanish from the conversation.