Dialogflow - Conversational UX Platform. (ex API.ai)
M for iOS - Email app with automatic encryption
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Hermes - Pandora Client for OS X
Botpress - Open-source platform for developers to build high-quality digital assistants
Keybase Chat - End-to-end encrypted chat built into Keybase