** Instant messaging
- https://letsconvene.im/ - browser-based conversations without accounts
- https://github.com/kiwiirc/plugin-conference - Jitsi/KiwiIRC integration
+ - https://github.com/esl/MongooseIM - XMPP server with SIP interop (see https://esl.github.io/MongooseDocs/latest/tutorials/Jingle-SIP-setup/ and https://esl.github.io/MongooseDocs/latest/modules/mod_jingle_sip/)
+ - https://wiki.linphone.org/xwiki/wiki/public/view/Flexisip/ SIP with (custom) push
** Password managers
- https://keeweb.info/ / https://github.com/PhilippC/keepass2android have built-in support for remote storage, so they do not rely on external file synchronization
** Networking