Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.
File Camouflage - Hide and encrypt files inside a jpeg image
Wickr - Wickr is a free end-to-end encrypted text, video, picture and voice messenger with full sender...
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Chatlink.com - Anonymous communication platform