XMPP is an open chat protocols that has / had been used by many Cloud providers to develop their own proprietary chat services - unfortunate almost zero of them contributed back.
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).
2. End-to-End Encryption
XMPP OMEMO provides a credible alternative to previous XMPP end-to-end encryption schemes.
Increasing number of XMMP client now supports the OMEMO end-to-end encryption standard:
3. Multi-User Chat
XMPP's Multi-User Chat (MUC) is not federated, which can be a problem in certain applications.
MUC federation standard has been proposed, but have no been taken up by the XMPP community at this stage.
XMPP Web Clients
Web browser based XMPP clients can be used without software installation on your device:
movim xmpp client.
converse.js xmpp client (has plugins).
jsxc xmpp client (available inside Nextcloud)
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, movim is an interesting one to try, since it has a blogging interface not found in most other XMPP clients.
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3 software are actively being developed as of 2022 so the above XMPP feature table is for reference only and will be out of date almost immediately after it is published.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:
XMPP Android Clients
There is currently no perfect XMMP client for Android.
- Conversations can search by messages while aTalk cannot.
- aTalk uses ZRTP to secure RTP streams while Conversations does not.