# Zulip

> Apache-2.0 team chat organised by topic threads; self-host or use Zulip Cloud

**Category:** Comms  
**Pricing:** open-source  
**URL:** https://zulip.com  
**GitHub:** https://github.com/zulip/zulip  
**Added:** 2026-10-21

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## The Hook

Zulip is open-source team chat where every message belongs to a channel and a topic, so conversations stay threaded and you can catch up topic by topic instead of scrolling one stream.

## What's Good

Apache-2.0 (zulip/zulip), server release 12.3 (2026-09-21), commit on 2026-10-21. ★~26k (~45 a week), developed since 2015. Useful for remote or open-source teams that want a Slack alternative they can self-host, with a REST API, bots and webhook integrations.

## The Catch

The self-hosted server is a substantial install (Postgres, RabbitMQ, Redis, memcached, nginx) and wants its own VM. Mobile push notifications from a self-hosted server go through Zulip's push service, which is only free up to a certain size. The topic model takes a week or two to get used to.

## Verdict

The best open-source Slack alternative if your team likes threads.