Domain and url for BOSH:
404.city - https://xmpp.404.city:5443/bosh - Registration https://404.city/
Birdie is a decentralized Echat *Like Email* platform also known as Jabber and XMPP, which later names are far from catchy to the puplic so brainstorming it through, here we go with Birdie!
Birdie is free from all the biggie criminals of sociaty who wanna take control over the internet and is completly open as far as I know, both the Server side and the User side of things - so for anyone who wants to flee and rest in some Sanity the free Birdie might be a way to go!
Now the Platform is not without its own issues but at least you get it more like the good old days and yet some travel still to get to that old lost saneness, like sending files directly to people without any conflict and without any walls like data limits and the possibility to easily resume if contact is lost - the platform needs more Programmers like German Chris who has created the very best and userfrindly Android Client for Birdie, known as Pix-Art forked from Conversations created mostly by German Daniel as far as I know - so that would be my choice of pick if you are going to try it out on a Spyphone *Android phone*.
You will run into your fair share of Germans on the platform, and nerdy nerds, so be aware of that. The Birdie platform also has big variation of clients for it, and I think I must have tested +20 just for Android as that is the device *LG V20* I have and Pix-Art clearly takes the first price although other interesting clients would be Yaxim which sadly I had some anoying issues with and jTalk which seems to be kinda unstable
I think most use Gajim for PC, which is also found in a portable version, but it seems slow on my old computer and it takes some time to set it up like you want - there are other more lightweight options although wrappers *program in a program or something like that* like Dino, Chimeverse and JSXC but in the end, I'm having my arms are up in the air and thinking just sticking with the Web client Converse which is found on this page down right for clicking and use.
It does get tedious to try out all those clients here and there to find something you like, but Pix-Art for Android, Gajim for PC seem to be the safe choices for most.