Messenger for Mac - Facebook Messenger wrapped up as a desktop app
Chatterino - Chatterino is a chat client for twitch chat.
Goofy - A Mac app for Facebook Messenger
Chatty - Chat with strangers all around the world in Messenger
Caprine - Elegant Facebook Messenger desktop app
Restream Chat - Restream Chat is a versatile software that permits you to streamline multiple chats in one place.