Zulip
Team chat organised by topic, so conversations are easy to follow.
Open source alternative toSlack
Similar open source projects
All Slack alternatives-
Rocket.Chat
Team chat with channels, threads and video calls, self-hostable.
Alternative to Slack
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Mattermost
A secure messaging platform for teams that you can self-host.
Alternative to Slack, Microsoft Teams
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Element
A Matrix chat client for the web.
Alternative to Discord, Slack
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Huly
An all-in-one project management platform: issues, docs, chat and team planning.
Alternative to Linear, Jira, Slack +1
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Colanode
A local-first workspace for chat and docs: an open-source take on Slack and Notion.
Alternative to Notion, Slack
About 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.