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?
Xmpp works great for 1:1 chats and small private groups, but there isn’t really an enterprise team chat client for it. Recently some promising projects came up trying to change that, but they are still too new to be serious contenders for that usecase specifically. Maybe in 1-2 years the situation will be different.