Hey there,
I’m on the search for an alternative to Mattermost for a small institution I’m working with. Mattermost was the strongest contender for our needs, yet they changed their policy regarding self-hosted instances. The factor that killed it for us, is the hard cap on 250 registered users, as we potentially might need to commodate more than that.
Rocket.Chat has similar caps.
We found Zulip, and it seems as it might be what we are looking for, but we haven’t tested yet. Nonetheless, I wanted to address this community, as you may have another good idea?


Of the ones I’ve tried that are fully open-source is the best ons regarding UX functionality.
For example, Matrix is a UX nightmare, with many different clients implementing different features, or having issues if a non-default login mode is used, ending in people getting locked out after the browser logged them out because they forgot to copy a key when they were logged in.
Others like rocketchat are opencore like matter most, which means they can do the switcheroo.
The things I would care the most when checking this kind of service are: