Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Crypho - End-to-end-encrypted messaging and file sharing
WhatsApp Desktop - WhatsApp, now on your desktop
blockslack.io - Chat for small teams — encrypted and decentralized
Wafer Messenger - Endless Creativity, Limitless Reach.
Wire by EY - A highly secured collaboration platform