ChatSecure is a messaging application for iOS which allows OTR and OMEMO encryption for the XMPP protocol. Developed by Chris Ballinger and The Guardian Project
License: Open Source
Tox is a decentralized communication platform focused on providing secure voice and video calls alongside text messaging, while ChatSecure emphasizes privacy with OTR messaging and integration with Tor. Both are open-source, but Tox offers broader communication features, whereas ChatSecure is more privacy-centric.