Gitter vs Let's Chat vs Mattermost

From a StackShare Community member: “We’re about to start a chat group for our open source project (over 5K stars on GitHub) so we can let our community collaborate more closely. The obvious choice would be Slack (k8s and a ton of major projects use it), but we’ve seen Gitter (webpack uses it) for a lot of open source projects, Discord (Vue.js moved to them), and as of late I’m seeing Spectrum more and more often. Does anyone have experience with these or other alternatives? Is it even worth assessing all these options, or should we just go with Slack? Some things that are important to us: free, all the regular integrations (GitHub, Heroku, etc), mobile & desktop apps, and open source is of course a plus."

Mattermost sports higher performance, uses Postgres, is a pure server side application not using up too much of system resources on the client side, and gives an overall enterprise grade impression in general.

Updates go smooth without a hassle, everything is organised logically, and the integration with the OS is absolutely stable. Apart from that, the underlying runtimes and code are mature, proven and stable.

The developers are maybe a bit more cautious in regard to introducing new features, but they maintain a stable experience, not breaking the codebase in order to hastily implement bells and whistles, which are not yet ready for production. Documentation and debugging are fantastic, so running this in enterprise production environment is absolutely approved of.