Rocket.Chat vs Mattermost
Rocket.Chat and Mattermost are the two best-known open-source, self-hostable team-chat platforms — both pitched as Slack alternatives you can run on your own infrastructure — so teams that have chosen self-hosted chat genuinely compare them, and their MCP servers let an agent participate in either. Both servers are community-maintained and cover the surfaces a chat assistant actually needs. The Rocket.Chat server (rocketchat-mcp) ships around 28 tools: list channels and groups, read channel and thread messages, search history and pull message context, send/edit/delete messages, reply in threads, send and read direct messages by username, and handle files, reactions, and pins. The Mattermost server is an actively maintained community integration that spans listing public and personal channels, creating and joining channels, opening direct channels, posting and editing messages, searching messages and users, working with threads and reactions, pinning messages, managing teams, and uploading or linking files — with an Entry+ edition adding channel-bookmark tools. So the two are remarkably close in capability; the decision is mostly which platform you run. Here is the comparison.
How they compare
| Dimension | Rocket.Chat | Mattermost |
|---|---|---|
| Platform | Rocket.Chat — open-source, self-hostable team chat, often chosen for flexibility and an open ecosystem. | Mattermost — open-source, self-hostable team chat with a strong security/compliance reputation in regulated environments. |
| Maintenance | Community server (rocketchat-mcp) with ~28 tools covering the core chat surface. | Actively maintained community server connecting assistants like Claude and Cursor to a self-hosted workspace. |
| Messaging surface | List channels/groups, read channel and thread messages, search, message context, send/edit/delete, thread replies, and DMs by username. | List public/personal channels, create/join channels, open direct channels, post/edit/delete, search messages and users, and thread replies. |
| Extras | Files (list/upload/download room files), reactions, and pins built into the tool set. | Reactions, pinning, team management, file upload/link, and an Entry+ edition adding channel-bookmark tools. |
| Best-fit task | Teams running Rocket.Chat that want an agent to read, post, search, and manage threads, DMs, files, and reactions. | Teams running Mattermost that want similar chat automation plus team management and bookmark tooling. |
Verdict
These two are close enough in capability that the choice almost always comes down to which platform you already self-host. Rocket.Chat's server gives an agent a clean ~28-tool surface over channels, threads, DMs, files, reactions, and pins. Mattermost's server matches that with channel and message operations, search over messages and users, team management, and an Entry+ tier adding bookmarks. If you're standardizing on Mattermost (common in security- and compliance-conscious orgs), use its server; if you run Rocket.Chat, use that one. Both are community-maintained, so weigh activity and fit, but functionally you can expect an agent to read, post, search, and manage threads and files on either.
FAQ
- Are these official servers?
- Both are community-maintained rather than vendor-official. The Rocket.Chat server (rocketchat-mcp) offers around 28 tools, and the Mattermost server is an actively maintained community project that connects assistants to a self-hosted workspace.
- Do both support threads and direct messages?
- Yes. Rocket.Chat reads and replies in threads and sends/reads DMs by username. Mattermost works with threads and can open direct channels and post messages, so an agent can handle both group and one-to-one conversations on either platform.