Olyo - Direct marketing via Facebook Messenger
Dialogflow - Conversational UX Platform. (ex API.ai)
Conte.ai - Conte.ai is a modern web-service for businesses of all sizes from any industry
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
MFY.im - Facebook Messenger sequences and growth widgets for creators
Botpress - Open-source platform for developers to build high-quality digital assistants