Zulip Terminal
Team ChatTerminal client for the Zulip team chat platform
Replaces Slack
Best Free Team Chat for self-hosting
The 4 best Free team chat you can self-host, ranked by community traction.
Spark IM
Team ChatCross-platform XMPP instant messaging client
Replaces Slack, Skype
matterircd
Team ChatConnect to Mattermost or Slack using any IRC client
Replaces Slack desktop client
Virola Messenger
Team ChatInstant messaging and collaboration tool with private and group chat
No apps match these filters.
Every option here is open-source and self-hostable, tagged Free within the team chat category. Compare them on the individual app pages for setup difficulty and resource requirements.