This is the great thing about having open standards supported applications, as they can intercommunicate securely using those standards with no lock-in to a single Facebook Messenger, WhatsApp, etc. Let's ignore the fact that Facebook Messenger of course once also supported XMPP....
Sign up once with any XMPP service and communicate with all other XMPP-using users, just like e-mail does with any other e-mail provider. One advantage that XMPP messengers have over e-mail though for encryption, is that the OMEMO encryption protocol is easier for most end users to get going, so it is more broadly used.
Kaiden runs on various flavours of Linux as well as Android, but you can actually use any XMPP client on Windows, macOS, iOS, etc to communicate with any XMPP user anywhere. The way messaging should be!!!
See
KDE's Kaidan Messaging App Adding Encrypted Audio/Video Calls#
technology #
opensource #
XMPP #
Kaidan #
openstandards [url=https://www.phoronix.com/news/Kaidan-Encrypt-Audio-Video-Call]
KDE's Kaidan app has been in development for a number of years now as a Jabber/XMPP chat client built around Kirigami and Qt Quick
