Free & Open-Source Slack Alternatives

Team messaging and channels.

1. Rocket.Chat ↗ FOSSPRIVATESELF-HOST
   Self-hosted Slack alternative with full feature set.
   ●●○Medium · Requires self-hosting
2. Element ↗ ★ PICKFOSSPRIVATESELF-HOST
   Matrix-based encrypted chat with bridges.
   ●●○Medium · Federated, no central server
3. Mattermost ↗ FOSSPRIVATESELF-HOST
   Open-source team chat for enterprises.
   ●●○Medium · Requires self-hosting