Self-hosted alternative to Slack
To replace Slack with something you control, three options cover it. For the closest Slack-style experience, Mattermost. For a flexible, customizable team chat, Rocket.Chat. For threaded conversations done differently and well, Zulip.
Updated 2026-06-03 · by Jonathan Caruso
Top pick
Mattermost
Mattermost is the closest drop-in for Slack: channels, threads, mentions, and integrations in a polished UI that feels familiar. For a team leaving Slack, it is the easiest switch.
The options
Mattermost
Open core, free CEA Slack-style team chat with channels, threads, and integrations.
Visit Mattermost site- Runs on
- Docker, ~2 GB RAM, needs Postgres.
- Pick it if
- You want the closest drop-in Slack replacement.
Rocket.Chat
MIT, freeA highly customizable team chat platform with many integrations.
Visit Rocket.Chat site- Runs on
- Docker, ~2 GB RAM, needs MongoDB.
- Pick it if
- You want flexibility and a lot of integrations.
Zulip
Apache, freeA team chat organized around topic-based threads inside channels.
Visit Zulip site- Runs on
- Docker, ~2 GB RAM.
- Pick it if
- You want Zulip's threading that keeps busy channels readable.
How to choose
If you want the most Slack-like experience for a team, Mattermost is the closest: channels, threads, integrations, and apps that feel familiar, with a polished UI. Rocket.Chat trades some polish for flexibility and a huge set of integrations and customization options, which suits teams that want to tailor everything.
Zulip takes a different approach with topic-based threading inside channels, which keeps busy conversations far more readable than Slack's model. If your team drowns in a noisy general channel, Zulip's structure is genuinely better. Pick by whether you want Slack-familiar (Mattermost), flexible (Rocket.Chat), or better-organized (Zulip).
The verdict
For the closest Slack replacement for a team, run Mattermost: familiar channels, threads, and integrations with a polished UI. Choose Rocket.Chat if you want maximum flexibility and integrations, or Zulip if your team would benefit from its topic-based threading. For a more Discord-like community instead of a Slack-like team, see our self-hosted alternative to Discord.
FAQ
What is the best self-hosted Slack alternative?
Mattermost, for most teams, because it is the closest to Slack with channels, threads, and integrations. Rocket.Chat is more customizable, and Zulip's topic-based threading keeps busy channels readable.
Is Mattermost really like Slack?
Yes, deliberately. It mirrors Slack's channels, threads, mentions, and integrations with a familiar UI, which makes it an easy switch for a team leaving Slack.
Can I migrate my Slack data?
Mattermost and the others provide Slack import tools that bring over channels and messages. Exact fidelity varies, so test the import with a copy before you commit.