End-to-end encryption (E2EE) is a digital communications system that facilitates two or more parties, known as communication endpoints, to communicate securely through an untrusted third-party, such as telecommunications service providers, Internet providers, or application service providers.
WhatsApp and Telegram, the two popular messaging apps, use this type of encryption but there are more available.
ChatSecure – iOS and Android app
Crypho – enterprise mobile chat and file-sharing (free plan for personal use)
Threema iOS, Android, Windows Phone paid app
surespot open source iOS and Android app
Cyph web service, doesn’t require registration
Confide Windows, Mac, iPhone and Android app
Darkwire chat via browser
Bit Chat Windows and Ubuntu Linux software
MEGAchat text as well as voice and video chat provided by the famous file hosting service
Signal free and open-source encrypted voice calling and instant messaging application for Android and iOS.
There are many alternatives, you just have to make the choice!