FluffyChat - Open. Nonprofit. Cute ?
Tox - Send messages, files, create groups and make Tox to Tox audio and video calls. Securely.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Molly (Signal fork) - Molly is an independent Signal fork for Android
uTox - µTox is the lightweight client with minimal dependencies; it not only looks pretty, it runs...
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.