Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption. Developed by Project Tox
License: Open Source
Tox is an open-source communication platform that emphasizes privacy and security without requiring personal information, while Threema is a paid app that focuses on providing a highly secure and anonymous messaging experience. Threema offers a more polished user experience and additional features but comes at a cost.