Apache-2.0freeRuns locallyWriting & Office
Zulip: Open-Source Slack Alternative
Apache-2.0 topic-threaded team chat you can self-host or run on Zulip Cloud.
- License
- Apache-2.0
- Stars
- 26,095 (2026-10-23)
- Platforms
- Linux, Docker, Web, Windows, macOS, Android, iOS
- First seen
- 2015-09-25
TL;DR. Zulip is Apache-2.0 topic-threaded team chat you can self-host or run on Zulip Cloud. License: Apache-2.0 (verified). Platforms: Linux, Docker, Web, Windows, macOS, Android, iOS. Price: free. Runs locally: yes. It is an alternative to Slack.
| Name | Zulip |
|---|---|
| Language | Python |
| License | Apache-2.0 |
| Pricing | free |
| Platforms | Linux, Docker, Web, Windows, macOS, Android, iOS |
| Runs locally | Yes |
| Stats | 26,095 stars · 10,457 forks (as of 2026-10-23) |
| First seen | 2015-09-25 |
| Repository | https://github.com/zulip/zulip |
Zulip is an open-source topic-threaded team chat app. Official hosts we opened on 2026-10-23: zulip/zulip (26,095 stars, 10,457 forks, created 2015-09-25, last push 2026-10-22T09:37:30Z, default branch main), LICENSE (Apache-2.0), release Zulip Server 12.3 (2026-09-21), and zulip.com.
It is listed on Slack alternatives as the Apache-2.0 topic-threaded option next to Mattermost. That mapping is editorial. We have no sourced quality comparison against Slack or Mattermost.
The README (opened 2026-10-23): “open-source organized team chat app with unique topic-based threading,” “designed for both live and asynchronous conversations.” Self-host on Ubuntu or Debian, Docker, or listed cloud images. Zulip Cloud is hosted SKU, not the Apache-2.0 grant. Those labels are copied.
Key facts (2026-10-23)
| Field | Value | Source |
|---|---|---|
| Stars / forks | 26,095 / 10,457 | GitHub API |
| Created | 2015-09-25T16:37:25Z | same |
| Last push | 2026-10-22T09:37:30Z | same |
| Latest release | 12.3, 2026-09-21T17:10:07Z | GitHub Releases |
| License | Apache-2.0 | LICENSE + GitHub API |
| Language | Python | GitHub API / README |
| Job | Topic-threaded team chat | README |
License
LICENSE is Apache License 2.0. GitHub license.spdx_id Apache-2.0. README restates Apache 2.0. Not legal advice.
Install (docs, not tested)
README: self-host on Ubuntu or Debian Linux, Docker (zulip/docker-zulip), or listed DigitalOcean / Render images. Cloud users go to zulip.com/zulip-cloud. forkalt has not installed Server 12.3.
Related
- Slack alternatives
- Mattermost (open-core Slack-shaped row)
- Writing & Office
- Workspace docs: Notion alternatives
- Chat models (not team chat): ChatGPT alternatives
FAQ
Is Zulip open source?
Yes on the file we opened. zulip/zulip LICENSE is Apache License 2.0 (2026-10-23). GitHub license field Apache-2.0. 26,095 stars, last push 2026-10-22. Not legal advice.
What version did you check?
GitHub Releases latest is Zulip Server 12.3 (tag 12.3, published 2026-09-21T17:10:07Z). Last push on main was 2026-10-22T09:37:30Z.
Does it replace Slack?
The README positions Zulip as organized team chat with topic-based threading (“combines the best of email and chat”). That is vendor copy, not a forkalt bake-off. See Slack alternatives. Mattermost is the Slack-shaped open-core row.
Sources & verification
- https://github.com/zulip/zulip
- https://github.com/zulip/zulip/blob/main/LICENSE
- https://github.com/zulip/zulip/releases/tag/12.3
- https://zulip.com
- https://zulip.com/self-hosting/
- https://commons.wikimedia.org/wiki/File:Zulip_screenshot_of_demo_content.png
License notes are not legal advice. Read the original LICENSE. Trademark & disclaimer.