[jacinda]

+1 to the other comments recommending Zulip over Mattermost. The threading model is fantastic.

Also, for a non-profit teaching coding note that they regularly have interns under the Google Summer of Code program and it's open source, so the students can even help with it.

https://summerofcode.withgoogle.com/programs/2025/organizati...

[thetridentguy]

I believe we considered Zulip, but determined it's mobile app to be poor.

[sundarurfriend]

When was it looked into? The Zulip mobile app was rewritten in Flutter recently, that version was in beta for several months and was finally made the default Zulip app about a month ago. I haven't used Mattermost so can't compare, but the Flutter Zulip is much more responsive and nice than the previous Zulip app.

[IshKebab]

Mattermost's mobile app is also pretty bad though.

[MaKey]

What's poor about it? I've used it for a while and didn't notice anything bad.

[4b11b4]

It's better these day

[pcthrowaway]

Mattermost is also open source, (AGPLv3 with lots of components optionally available via MIT or Apache terms). It does require contributors to sign a CLA though (unlike Zulip as far as I can tell?), and this likely reduces community involvement.

Mattermost has threads, though they work different from Zulip.

I haven't used both extensively, and for an open community like Hack Club, I suppose it's possible Zulip may even be a better fit. Mattermost will offer a much more direct migration path from Slack however.

I'm curious what makes some recommend Zulip so highly over Mattermost.