the open source movement

Replace Slack.

6 open source alternatives, ranked by health. We re-check every project weekly, so you don’t migrate to something abandoned.

Ranked by health

  1. Rocket.ChatTeam communication platform with chat, channels, video calls and integrations, built for self-hosting.★ 46k MIT + commercial ee/ TypeScript self-host managed
  2. MattermostSelf-hosted team chat and collaboration platform with channels, threads, calls and integrations.★ 39k AGPL-3.0 + commercial enterprise TypeScript self-host managed
  3. ZulipZulip server and web application. Open-source team chat that helps teams stay productive and focused.★ 26k Apache-2.0 Python self-host managed
  4. ElementMatrix chat client for the web with end-to-end encrypted messaging, rooms and calls.★ 14k AGPL-3.0 TypeScript self-host managed
  5. ChattoA fully-featured team and group chat application that you can easily selfhost.★ 2.8k AGPL-3.0 TypeScript self-host
  6. QuietPrivate peer-to-peer team chat app built on Tor and IPFS, with no central server.★ 2.7k GPL-3.0 TypeScript self-host
How the ranking works

Health blends commit recency, release cadence, issue throughput, contributor breadth and star growth. Stars are shown but never ranked on. The full method.