Matterbridge
Team ChatBridge messages between many chat platforms
Replaces Slack
Best Cross-Platform Team Chat for self-hosting
The 4 best Cross-Platform team chat you can self-host, ranked by community traction.
Zulip Terminal
Team ChatTerminal client for the Zulip team chat platform
Replaces Slack
Spark IM
Team ChatCross-platform XMPP instant messaging client
Replaces Slack, Skype
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 Cross-Platform within the team chat category. Compare them on the individual app pages for setup difficulty and resource requirements.