Slack vs Zulip
Slack and Zulip are both team chat software. Slack is a commercial product from Salesforce, Inc. Zulip is open source under Apache-2.0, with 26k GitHub stars.
Which to pick
- Pick Slack when
- A team wants the chat tool with the widest integration ecosystem and is willing to pay per seat.
- Pick Zulip when
- Your team finds Slack threads chaotic and wants organised, asynchronous conversations, self-hosted or hosted.
Side by side
Team messaging organised into channels and threads, with huddles, shared channels between companies, workflows and thousands of app integrations.
A team chat server and web app built around topic-based threads within channels, with desktop and mobile clients.
Per-seat pricing is high, the free plan hides history older than 90 days, and Salesforce keeps tightening API access.
The topic model takes adjustment, and self-hosted push notifications go through Zulip's paid service for larger teams.
Production-ready (both)
Cloud service, desktop app and mobile app
Self-hosted server, cloud service, desktop app and mobile app
Not published
Python, Django, TypeScript, PostgreSQL and Redis
Closed source, sold by Salesforce, Inc.
Open source, Apache-2.0 (permissive)
Closed source: you use it under the maker's terms and cannot change or resell the code.
You can build it into a product you sell, as long as you keep its copyright notice.
8.4k Wikipedia readers a month on phones
26k GitHub stars
Not known
Established: started 11 years ago, latest release 12.3.
Other comparisons
More team chat apps
Both sides were judged on 2026-11-03 from makers' descriptions, Wikipedia, READMEs and GitHub data. License, age and popularity lines are worked out directly.