Open source alternatives to Slack
6 free tools that do the job of Slack, most stars first. All are web apps you can run on your own server.
JobTeam chat
6 alternatives
Sorted by most stars.-
Rocket.Chat
Team chat with channels, threads and video calls, self-hostable.
Web app
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Mattermost
A secure messaging platform for teams that you can self-host.
Also an alternative to Microsoft Teams
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Huly
An all-in-one project management platform: issues, docs, chat and team planning.
Also an alternative to Linear, Jira, Notion
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Zulip
Team chat organised by topic, so conversations are easy to follow.
Web app
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Element
A Matrix chat client for the web.
Also an alternative to Discord
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Colanode
A local-first workspace for chat and docs: an open-source take on Slack and Notion.
Also an alternative to Notion
More alternatives in Team chat
All Team chat tools
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Ask us to add itAbout these numbers. Stars, dates and licenses come from GitHub through ecosyste.ms, collected on 10 Nov 2026; they can lag GitHub by a few days. A project is listed only if it has 300 or more stars, was updated in the last 12 months and states a license. A listing is not an endorsement, and we have not tested these tools on Antideploy yet. Logos belong to their projects and companies and are shown only to say which is which.