Name: Discord
Homepage: https://discord.com/
Short description: Discord is a VoIP, instant messaging and digital distribution platform. Users communicate with voice calls, video calls, text messaging, media and files in private chats or as part of communities called "servers". - Wikipedia
Optional API documentation URL: https://discord.com/developers/docs/
You could implement this provider like you did on Matrix. Something like: Join a channel or server, post a message ...