Jabber/XMPP is an open-source instant messaging protocol first released in 1999.
It takes on new life these days by providing a Big Tech alternative to instant messaging.
We have operated a Jabber server since 2012 and make the service available to anyone looking to disconnect from Big Tech.

Advantages:
No server-side chat logging
No censorship
Federation with other indepenent XMPP servers (add contacts on other servers)
TLS Client/Server encryption
Optional end-to-end OTR encryption (client specific)

Recommended Clients
Windows/Mac: Spark
Linux: Pidgin
Android: Xabber - APKs available here
iOS: AstraChat

Server Details
Typical client logs in with username: you@jabber.rocket-tech.net
Server name: jabber.rocket-tech.net
Port: 5222
Encryption: Require TLS (not old-style SSL)
File transfer proxy: jabber.rocket-tech.net:7777