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 robust open-source video conferencing solution with strong privacy features, while Disa focuses on integrating multiple messaging platforms into one customizable interface. Jitsi is ideal for video meetings, whereas Disa excels in messaging capabilities.