There are many chat thingies out there. Skype is quite often very slow when we communicate between continents as of late. So I took it on myself to look for a relatively similar chat application that is browser based and that I am able to host myself. Installing (unvetted) clients is a definite no-no in the places with which I need to communicate. But browsers are much less of a (legal) problem.
Mattermost is one of the more interesting self-hosted options out there, but it relies on NGINX (or however you spell their name) web server software. And that is not what I'm using. Alternatives are a dime a dozen, but not nearly as useful as they promise to be. So I do get where Tuxman's "aversion" to yet another chat app comes from. At least I think I do.