Mattermost
Team Chat
Self-hosted team chat with channels, calls, playbooks and boards, as a free MIT build or a commercial subscription.
Free self-hostedProprietary
Also offers paid editions — see the detail.

Chat for a small team or a client project, hosted on your own server with your own history and retention rules.
3 entries
Team Chat
Self-hosted team chat with channels, calls, playbooks and boards, as a free MIT build or a commercial subscription.
Also offers paid editions — see the detail.
Team Chat
Self-hosted team chat with messaging, voice and video; free Starter and MIT Community editions, paid plans by quote.
Also offers paid editions — see the detail.
Team Chat
Open-source team chat with topic-based threading, self-hosted on your own Ubuntu or Debian server.
Also offers paid editions — see the detail.