Secure Messaging Apps Comparison | Privacy Matters

This site compares secure messaging apps from a security & privacy point of view. These include Facebook Messenger, iMessage, Skype, Signal, Simple...

While XMPP is fine as you suggest, I don't like offering services to others—it's not worth it. The combination of Signal and Simplex is my favorite.

Then you can help others to have their own services, but it does not scale. Simplex may scale while we can run some servers, not as centralised as signal.