# 3 Best Open-Source Alternatives to Mattermost in 2026

By Noah — last updated & pricing verified September 15, 2026.

> 3 of the 6 Mattermost alternatives we list qualify for this filter. The [full list](https://findalternative.to/mattermost) is the canonical page.

| Alternative | Best for | Price | Details |
| --- | --- | --- | --- |
| Rocket.Chat | regulated and security-conscious organizations (government, defense, healthcare, financial services) that need a self-hostable or air-gapped team chat platform, plus teams wanting a free, open-source Slack alternative | Free | https://findalternative.to/rocket-chat/about |
| Zulip | distributed and remote teams, open-source projects, and research groups who need many parallel conversations to stay organized without a flat, scrolling chat feed | Free tier · paid from $3.50/mo | https://findalternative.to/zulip/about |
| Element | government, defense, and enterprise organizations that need self-hosted, end-to-end encrypted chat with the option to federate across organizational boundaries | Free | https://findalternative.to/element/about |

All 6 alternatives to Mattermost: https://findalternative.to/mattermost

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Markdown mirror of https://findalternative.to/mattermost/open-source — findalternative.to, honestly ranked software alternatives. AI info: https://findalternative.to/ai