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 video conferencing tool with strong security features and self-hosting capabilities, making it ideal for privacy-conscious users. QuteCom, while offering VoIP and multi-platform support, lacks some modern features and has less active development, making it less suitable for users seeking advanced functionalities.