Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application. Developed by University of Strasbourg (France), plus many others.
License: Open Source
Jitsi is a versatile, open-source platform primarily focused on video conferencing and secure communication, making it ideal for group meetings and collaborations. In contrast, Yahoo! Messenger was a widely used instant messaging service that has been discontinued, lacking modern features and security protocols, which limits its current relevance.