You've pretty much covered all the open source alternatives, other than rocket.chat which is more similar to slack. This has a good list - https://medium.com/@j

You've pretty much covered all the open source alternatives, other than rocket.chat which is more similar to slack. This has a good list - https://medium.com/@jingjunm/the-best-alternatives-to-discord-ranked-a9deedf723b8 https://medium.com/@jingjunm/the-best-alternatives-to-discor... If you don't NEED the open-source, pumble and steam group chats work great too