Matrix is an open protocol for real-time communication. It is designed to allow users with accounts at one communications service provider to communicate with users of a different service provider via online chat, Voice over IP, and Videotelephony. Developed by Matrix.org
License: Open Source
ejabberd is a highly scalable XMPP server ideal for large deployments with strong user management features, whereas Matrix.org offers a decentralized architecture with rich media support and a focus on real-time collaboration. While ejabberd leans more towards traditional messaging protocols, Matrix provides a more modern approach to communication.