Rocket.Chat
Team chat platform with channels, threads, video, and broad integration marketplace.
Why it is included
Widely deployed open alternative to proprietary team chat with on-prem and air-gapped stories.
Best for
Enterprises and regulated teams needing chat under their own domain.
If you use Windows, Mac, or paid tools
Chat alternative to Slack, Microsoft Teams, and Google Chat when self-hosted.
Strengths
- Feature breadth
- Federation experiments
- Marketplace
Limitations
- Operational complexity at scale
Good alternatives
Mattermost · Zulip · Matrix/Element
Related tools
Communication & Collaboration
Mattermost
Team messaging platform with strong self-hosted enterprise adoption.
Communication & Collaboration
Element (Matrix)
Matrix client for federated, E2EE-capable real-time communication.
Communication & Collaboration
Zulip
Thread-first team chat combining email-like topics with real-time messaging.
Communication & Collaboration
Delta Chat
Messenger using email as transport—chat over your existing IMAP/SMTP accounts.
Communication & Collaboration
Matrix
Open standard for decentralized, encrypted real-time communication; reference server Synapse.
Communication & Collaboration
Wire
E2E-encrypted team chat, calls, and file sharing.