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 primarily a video conferencing tool that offers robust features for online meetings and collaboration, while YakYak is a messaging client focused on providing a lightweight chat experience. Jitsi excels in group video calls and security, whereas YakYak is ideal for users looking for a fast and simple messaging solution.