Nextcloud has a JavaScript XMPP Chat client, which can optionally be backed with a XMPP (Jabber) server (Prosody or ejabberd) and this enables any XMPP client to be used with the server.
Today I have installed and configured Prosody on office.coops.tech using the Ansible Playbook on git.coop and it would be great if people could give it a try, perhaps, in time, it could replace Slack…
There are a lot of XMPP clients to choose from, I have found Gajim (Linux / Windows) works fine on a desktop / laptop and Conversations (Android) is fine on a mobile and I have posted links to these on the (work in progress) Webarchitects Nextcloud wiki page.
The office.coops.tech server is setup with two XMPP chat servers, one at conference.office.coops.tech on which only people with Nextcloud accounts on our server can access and one at public.office.coops.tech which anyone with a XMPP account on any server can access.
Your XMPP username is in the form username@office.coops.tech and the password is the Nextcloud account password.
I have created a cotech@public.office.coops.tech chatroom, pop by and say hi!