> /v1/alternatives/slack
Open source alternatives to Slack[007]
Slack real-time team chat, channels, threads, integrations. Below are 7 self-hostable open source alternatives, ranked by GitHub popularity.
Rocket.Chat
The communications platform that puts data protection first
★ STARS
45.3k
⑂ FORKS
9.9k
Mattermost
Mattermost is an open source platform for secure collaboration across the entire software development lifecycle
★ STARS
36.6k
⑂ FORKS
8.6k
Zulip
Zulip server and web application. Open-source team chat
★ STARS
25.2k
⑂ FORKS
9.8k
Matrix (Element)
A glossy Matrix collaboration client for the web
★ STARS
13.1k
⑂ FORKS
2.6k
Wire
A comprehensive collaboration platform offering end-to-end encrypted messaging, file sharing, and video calls with enterprise-grade security and compliance features.
★ STARS
2.5k
⑂ FORKS
179
Elementary
Open-source data observability for data teams
★ STARS
2.3k
⑂ FORKS
214
ProcessWire
A versatile, open-source content management system with a powerful API, modular architecture, and intuitive interface for seamless web development.
★ STARS
1.1k
⑂ FORKS
206
// EDITOR'S TAKE
Mattermost is the closest feature-for-feature; Rocket.Chat is more flexible; Zulip handles threaded conversations better than Slack itself.
// FREQUENTLY ASKED
What is the best open source Slack alternative?
Rocket.Chat is the most popular open source Slack alternative by GitHub stars (45,269 stars). The other 6 options are ranked above.
Are these Slack alternatives self-hostable?
Yes — every project listed here is open source and runs on your own infrastructure. Click into a project to see its license, stars, language, and current health status.
Are they free?
All projects shown are free and open source. Check each project's license page for the terms — most are MIT, Apache 2.0, or AGPL.