Keybase Chat - End-to-end encrypted chat built into Keybase
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Seald - Keep your conversations secure, everywhere.
Facebook Messenger - Facebook Messenger is a faster way to message.
Hermes - Pandora Client for OS X
Amity - Amity's Customer Relationship Hub simplifies customer success management.