Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
ChatIW - Meet and Chat with new friends around the world.
Keybase Chat - End-to-end encrypted chat built into Keybase
ChatSecure - ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
Crypho - End-to-end-encrypted messaging and file sharing
Otr.to - A secure peer-to-peer chat in your web browser.