Microsoft Bot Framework - Framework to build and connect intelligent bots.
ChatBot - Easy to use chatbot platform for business
Botpress - Open-source platform for developers to build high-quality digital assistants
Amazon Lex - Harness the power behind Amazon Alexa for your own conversational apps.
Dialogflow - Conversational UX Platform. (ex API.ai)
rasa NLU - A set of high level APIs for building your own language parser