Crypho - End-to-end-encrypted messaging and file sharing
Dialogflow - Conversational UX Platform. (ex API.ai)
blockslack.io - Chat for small teams — encrypted and decentralized
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Wire by EY - A highly secured collaboration platform
Botpress - Open-source platform for developers to build high-quality digital assistants