Open source team chat software in 2026: what to know
What open source really means for team chat, the main projects, and the questions that matter before you pick one.
The short answer
Open source team chat means the code is published under a licence that lets you inspect it and usually run it yourself. It does not always mean free of cost, free of paid editions or easy to run. Mattermost, Rocket.Chat, Zulip and Element (Matrix) are the best-known projects.
Licences and editions change, so read each project's current licence page before you decide. Dock is self-hosted software too; read its licence page for terms.
Questions that matter more than the logo
Which features are in paid editions?
Single sign-on, compliance and some admin tools often are.
How hard is it to run?
Count services, databases and upgrade steps.
How active is the project?
Recent releases and a healthy community.
What about meetings, docs and tasks?
Chat alone may mean more tools.
The well-known projects
| Project | Known for | Note |
|---|---|---|
| Mattermost | Chat-first teams and integrations | Some features in paid editions |
| Rocket.Chat | Many channels and omnichannel use | More to operate |
| Zulip | Topic-based threading | Different habit from channels |
| Element (Matrix) | Open protocol and federation | More setup |
| Dock | Chat, meetings, docs, tasks and AI agents in one app | Young; check its licence page |
Where Dock fits
Dock is a self-hosted team workspace for small teams. It has channels and DMs with threads and search, video meetings in the same app (with recording, transcripts and AI summaries), real-time docs, tables, calendar, tasks and a drive. An MCP server lets AI agents such as Claude Code read and post in your channels, and there is a Lark history import.
It runs as one Node process with one SQLite file, so backups and moves are copying a file. There is no per-seat licence; your cost is your own server. You run the server yourself, and the integration list is smaller than the big hosted tools.
What makes Dock different: it connects to your tools
Dock connects the places your team already works. Notion: connect your Notion pages, then type @notionpage_ in any chat to tag a page; everyone gets a preview card and your AI agents can read it. GitHub: link GitHub read-only, pin repositories to a chat, tag them with @github_ and ask the AI about them. Claude and Codex: use your own Claude or Codex plan inside Dock chats, or connect any MCP agent to your workspace with a token.
All of this sits next to chat, video meetings (with recording, transcripts and AI summaries), docs, tables, calendar, tasks and a drive, in a self-hosted app with no per-seat licence. You run the server yourself, and some integrations are young, so check the setup guides for what each one covers.
Questions
Is open source team chat free?
The software may be free to run, but you pay for a server and your time. Some features may need paid editions.
Is open source more secure?
Visible code helps, but your security depends on how you run and update it.
Which is easiest to run?
Fewer moving parts is easier. Check each project's install docs.