Crypho - End-to-end-encrypted messaging and file sharing
Keybase Chat - End-to-end encrypted chat built into Keybase
MushRoom - KnockKnock the person whom you want to message and he/she should accept your knockRoom or Group can be created by providing a nameShare Room link with your friends to join the conversationWatch video or listen music during conversation
Hermes - Pandora Client for OS X
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Brie.fi/ng - Start secure group video chat