Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Dialogflow - Conversational UX Platform. (ex API.ai)
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.
Crypho - End-to-end-encrypted messaging and file sharing
Botpress - Open-source platform for developers to build high-quality digital assistants