Keybase Chat - End-to-end encrypted chat built into Keybase
Xifrem Chat - Client-side encrypted chat with asymmetric encryption
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Brie.fi/ng - Start secure group video chat
Crypho - End-to-end-encrypted messaging and file sharing
YEO Messaging - Next generation communication platform, for your eyes only