Zulip

Zulip is an open source team chat app whose model stands out for organizing messages into "topics" within channels. Where other tools stack messages into one continuous stream, Zulip files each conversation under a named thread, which makes asynchronous follow-up easier.

What is Zulip for?

You chat in channels, but each message belongs to a specific topic, like an email thread. This lets you follow a discussion without getting lost, come back to it later, and catch up on channels asynchronously. Zulip offers powerful search, integrations, calls, and an open API. Its biggest strength: the code is open source and self-hostable, making it an excellent choice for teams focused on data sovereignty and GDPR.

Zulip or Slack?

Compared to Slack or Mattermost, Zulip bets on its topic-based model, which is easier to follow for asynchronous work and large distributed teams. Compared to Twist, also built for async work, it adds open source code and self-hosting. For a technical team that wants to own its data, it's a credible alternative.

How much does Zulip cost?

The Cloud Free plan is free (10,000 searchable messages of history, 5GB of storage). The Standard plan costs $6.67/user/month billed annually ($8 monthly), Plus is $10/user/month (SAML SSO, SCIM, 10-user minimum), and Enterprise is custom-quoted. The self-hosted version is free, and Zulip is offered free to nonprofits, education, and research.