We've used Mattermost for a small amount of time and then migrated to Zulip (company of about 50 people). Zulip's threading model is what sets it apart. It migh

We've used Mattermost for a small amount of time and then migrated to Zulip (company of about 50 people). Zulip's threading model is what sets it apart. It might take sometime to get used to but once you do you don't want to use anything else. Mattermost is primarily a Slack clone while Zulip is its own category. I think Slack style chat works best if everyone is working on the same thing; like a 5 man startup. However with more people working on all kinds of different things Zulip's model works better.