Does anyone else here use Mattermost, an open source, self-hosted alternative to Slack? I like it. We're not allowed to store communication offsite. I have no experience with Slack, so I'm wondering how current offerings compare.
Past HN discussion: https://news.ycombinator.com/item?id=17031306
Like Mattermost Zulip can be self-hosted, although we use the online paid for version.
Zulip's USP is the 'topic' system which group messages in each thread into a coherent conversation. It makes it much easier to look back over a set of conversations and see what happened. It works really well. It's let down by the mobile apps though, which are clunky and don't behave reliably.
The web-app is excellent though and the topic system does (just) win out over the crap apps. I do wish they'd sort them out though, both for me and so I could make an unqualified recommendation.
Boy, I mentioned Slack a lot.