XMPP is an open chat protocols that has been around for more than 25 years and is still going string.
It has / had been used by many Cloud providers (Google, Facebook etc.) to develop their own proprietary chat services. Unfortunately after using XMPP as a quick start to suck in their user base almost zero of them contributed back, in fact most went opposite to its philosophy and cut off XMPP support to lock their user base in.
1. Competitive Protocols
Although much older, XMPP has been constantly evolving, enabling it to keep up with newer federated messaging protocols like Matrix (e.g. used by Element) and Activitypub (e.g. used by Mastodon).
Private Cyberspace works with ANY chat protocol e.g. Rockchat, some reasons why Matrix is not the default protocol:
All support end-to-end encryption using OMEMO (although might not cover all information exchanges e.g. encrypted text chat but not file sharing).
If you do not have a strong preference, converse.js is ALREADY bundled inside your Private Cyberspace while movim is quite interesting, since it has a blogging interface not found in most other XMPP clients.
Below we are comparing those 2 web clients with each other and with another popular but less active web client called jsxc which is available as an option inside Data Nodes under the Nextcloud module.
All 3 software are actively being developed as of 2022 so the above XMPP feature table is for reference only and will be out of date almost immediately after it is published.
Some other interesting XMPP Web Clients we have yet to play with: