FluffyChat - Open. Nonprofit. Cute ?
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
WhatsGreen Multi Messenger - Easy access to WhatsApp, Line, Telegram, FB Messenger and many others via the Chrome toolbar.
Molly (Signal fork) - Molly is an independent Signal fork for Android
Sesame Chat - A Self-Aware, Digital Assistant that Protects Your Messages