Welcome to the new part of Free Messenger Saga (Signal, Tox, Matrix, Tor Messenger). It’s very good that in the modern world of Facebook, WhatsApp and Skype some peoples create new software for communication.
Ring – open source platform for text chat, voice and video communications and released under one of the best free license – GPLv3. All source code is available on Github. Linux client uses the GTK+ toolkit. Probably most of the Ring code was written by Savoir-faire Linux – free and open source software company based on Canada and France.