# Zulip

> Zulip is a mature, fully open source (Apache-2.0) team chat where every message sits in a named topic inside a channel, which suits async work. Self-hosting needs Ubuntu 22.04+ or Debian 12+, 2 GB RAM plus swap (4 GB and 2 CPUs for 100+ users) and 10 GB disk. Mobile push notifications go through Zulip's service, which needs a paid or sponsored plan above 10 users. Calls are not built in: Zulip adds a link to Jitsi, Zoom or another provider.

- Repository: https://github.com/zulip/zulip
- Official docs: https://zulip.readthedocs.io/en/stable/production/install.html
- Checked: 2026-10-15

## What it replaces
- Slack: Channels and direct messages, Threaded conversations, Integrations, Search and message history (partial). Topic threading replaces Slack threads; no built-in huddles (call links via Jitsi or Zoom). Mobile push above 10 users needs a plan.

## Facts, with sources

| Question | Status | Answer | Source | Checked |
|---|---|---|---|---|
| Runs on my machine? | Confirmed | Self-hosted server on Ubuntu or Debian, or hosted Zulip Cloud | https://zulip.readthedocs.io/en/stable/production/requirements.html | 2026-10-15 |
| Code licence | Confirmed | Apache-2.0 | https://github.com/zulip/zulip/blob/main/LICENSE | 2026-10-15 |
| Model weights licence | Confirmed | No separate model weights | https://github.com/zulip/zulip#readme | 2026-10-15 |
| Commercial use | Confirmed | Yes, Apache-2.0 with no user caps on the self-hosted server | https://github.com/zulip/zulip/blob/main/LICENSE | 2026-10-15 |
| Paid services needed? | Partial | None required; the Mobile Push Notification Service needs a paid or free Community plan for organisations over 10 users | https://zulip.readthedocs.io/en/stable/production/mobile-push-notifications.html | 2026-10-15 |
| Hardware | Confirmed | 1 CPU and 2 GB RAM with 2 GB swap for small teams; 2 CPUs and 4 GB RAM for 100+ users; 10 GB free disk | https://zulip.readthedocs.io/en/stable/production/requirements.html | 2026-10-15 |
| Operating systems | Partial | Server on Ubuntu 22.04+ or Debian 12+ only; desktop and mobile apps connect to it | https://zulip.readthedocs.io/en/stable/production/requirements.html | 2026-10-15 |
| Setup effort | Confirmed | Medium; download the release and run the installer script on a dedicated server | https://zulip.readthedocs.io/en/stable/production/install.html | 2026-10-15 |

GitHub: 26054 stars, 10410 forks, last push 2026-10-16, archived: no.
---
Source: RepoQuarry (https://repoquarry.dev/projects/zulip). Data licence: CC BY 4.0. Quotes are from project documentation and belong to their authors.