Powerful, modern, open source group chat, complete with apps for every major platform.

Zulip is a powerful, open source group chat application. It competes with Slack, IRC, Jabber, and dozens of other group chat tools designed to help teams (whether open source projects or at companies) collaborate effectively. Zulip supports fast search, drag-and-drop file uploads, image previews, group private messages, audible notifications, missed-message emails, desktop apps, markdown message rendering, and much more -- essentially everything you might want.

Unlike Slack, it’s open source and has a welcoming community of over 350 volunteer contributors. Unlike IRC/Jabber/etc., Zulip is a complete, modern application, with a web version, mobile apps for iOS and Android, and desktop apps for Mac/Linux/Windows. And unlike all other popular group chat tools, Zulip is designed to make conversations more efficient through its unique threading system that helps teams manage large numbers of messages. In particular, Zulip makes it easy to have multiple conversations at the same time with the same groups of people, and easy to catch up on hundreds or thousands of messages quickly without missing anything important.

Zulip is known for its extensive developer documentation (100,000 words and growing!), code quality, and tooling, and thus is a great project to work on to learn how to build a high-quality web application.

We have tons of tasks across all parts of the Zulip project, and we're especially excited about expanding Zulip's library of bots and integrations!

Primary Open Source License: Apache License 2.0 (Apache-2.0)

Programming Languages:

  • python
  • javascript
  • django
  • html
  • visual design


  • chat
  • bots
  • integrations
  • fun
  • great tooling