Wit.ai - Easily create text or voice based bots that humans can chat with on their preferred messaging...
Dialogflow - Conversational UX Platform. (ex API.ai)
Botsify - Ever wonder if you could replace your live chat support system with a chatbot?. Its possible now with Botsify Chatbot For Website.
Botpress - Open-source platform for developers to build high-quality digital assistants
Meya.ai - Build, train and host sophisticated bots.
ChatBot - Easy to use chatbot platform for business