Dialogflow - Conversational UX Platform. (ex API.ai)
VISEO Bot Maker - Create chatbots and vocal apps in just a few clicks
Botpress - Open-source platform for developers to build high-quality digital assistants
Meya.ai - Build, train and host sophisticated bots.
Messenger Platform - Discovery, chat extensions, and richer experiences
Amazon Lex - Harness the power behind Amazon Alexa for your own conversational apps.