We've been testing out both Mattermost and Zulip over the past few months at work, and we recently decided to go with Zulip. Mattermost is nice in that communi

We've been testing out both Mattermost and Zulip over the past few months at work, and we recently decided to go with Zulip. Mattermost is nice in that communication and project management is all in one tool, but doing anything within Mattermost is very sluggish (even on a very overspecced server with only 1 Mattermost user online). Using their Focalboard plugin resulted in multiple seconds of wait time between various actions like modifying a task. On the other hand, Zulip has been consistently snappy even as we've onboarded users onto our instance. Seeing it in use at large organizations such as Rust's Zulip instance instilled confidence that it'll continue to perform well even well beyond our scale. Also Zulip's threading model is really nice to use once you and your team gets the hang of topic separation. We've managed to completely eliminate 'talking over one another' as we would in Slack/Discord style text channels, and it's much easier to keep track of various conversations. While Zulip's UI and UX isn't as polished and certainly has areas for improvement, the threading model alone makes it worthwhile to use. On top of that, Mattermost's pricing doesn't work well for small businesses, especially when you factor in that something 'simple' like Elasticsearch support, or, performance monitoring tools to figure out why your 1 user installation on a 88 thread server with hundreds of GBs of memory is sluggish, or even just creating a second admin user is locked behind their enterprise plan. I get that money needs to be made, but blocking some features behind an enterprise plan (that asks you to contact them for pricing, no less - their $10/user for the Professional plan is not only steep, but still doesn't include these features) doesn't feel great. Zulip is completely free, and offers Zulip Cloud alongside a support plan, but does not block any features behind a paywall. There's no limitations on what Zulip will let you do either - no 10,000 message history limit, no file storage limit, user role restrictions, or anything of that nature. Oh, and Zulip is 100% open source software. In my eyes, it's hard to compete with that when it comes to communication tools.