Keybase Chat - End-to-end encrypted chat built into Keybase
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Crypho - End-to-end-encrypted messaging and file sharing
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
dPhone - The most secure calling app. Open Source and Free.
Brie.fi/ng - Start secure group video chat