XMPP

Extensible Messaging and Presence Protocol (XMPP), formerly known as Jabber, is a real-time communication protocol based on XML. The protocol is an open standard and allows federated messaging between different servers and clients. XMPP is extensible and in active development.

Some examples of specified features are:
 * Direct and group chat messages
 * Encryption e.g. via OMEMO or OpenPGP
 * File transfer
 * Audio/video calls
 * Typing notifications
 * Message receipts
 * Message correction

Servers
A few XMPP servers are available in the main Gentoo repository:

Clients
A few XMPP clients are available in the main Gentoo repository: