Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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.
TeleGuard - TeleGuard is a secure messenger that makes it store that your data or chats are not stored while collaborating or communicating with partners and friends.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Molly (Signal fork) - Molly is an independent Signal fork for Android