Zulip
Team chat organised by topic, so conversations stay readable
Alternative toSlack
Zulip is a team chat where every message belongs to a channel and a topic, which makes it possible to follow several conversations without losing the thread. The server is Apache-2.0 and self hostable, and the company behind it sells a hosted cloud and support plans.
Best for when
- your team or community talks in many parallel conversations
- people read and reply asynchronously across time zones
- you want chat history on your own server
Watch out for
- the topic model takes getting used to for people coming from Slack
- it wants a dedicated server and runs several services, so it is not a tiny container
- mobile push notifications rely on Zulip's relay service and its terms
Threads as the default, not an afterthought
In most chat apps, a busy channel is one long stream where questions get buried. Zulip asks for a topic with every message, a short subject line, so a channel splits into many small conversations. You can catch up topic by topic, mute the ones you do not care about, and link to a whole discussion later.
It suits distributed teams, open source communities and study groups where people read asynchronously across time zones. It has web, desktop and mobile apps, integrations with git forges and CI, and a full export for moving between cloud and self hosted.
What running it involves
The recommended install is a dedicated Ubuntu or Debian server, where the installer sets up PostgreSQL, RabbitMQ, Memcached, Redis and Nginx. Plan for at least a couple of gigabytes of RAM and grow from there with users. A Docker image exists, but the installer path is the main one.
Mobile push notifications from a self hosted server go through Zulip's push notification service, which needs registering your server and, depending on your size and use, a paid plan. It must be reachable by your users, so it is a public service: keep it updated, use HTTPS and back up the database and uploads.
