Best Slack Alternatives
Real-time channel chat platform. Teams seek alternatives to retain unlimited message history without high per-seat costs, organize async threads cleanly, or host chat behind a private firewall.
Communication · Markdown Spec
- Mattermost — Self-hosted open-source collaboration built for engineering & DevSecOps (Score: 67.1, Open Core, MIT / Enterprise)
- Zulip — Topic-threaded open-source team chat designed for deep async focus (Score: 64.3, Free & Open Source, Apache-2.0)
- Rocket.Chat — Self-hosted omnichannel team chat with Matrix federation and E2EE rooms (Score: 57.0, Open Core, MIT / Enterprise)
- Element (Matrix) — Federated, end-to-end encrypted messaging on the open Matrix protocol (Score: 52.0, Open Core, Apache-2.0)
- Campfire (ONCE) — Pay-once, own-forever self-hosted web chat with full source code by 37signals (Score: 49.7, Commercial, Source-Editable One-Time)
- Twist — Async thread-first calm team communication built by the makers of Todoist (Score: 45.8, Freemium, Proprietary)