Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
PyText - Facebook's open source conversational AI tech
Botsify - Ever wonder if you could replace your live chat support system with a chatbot?. Its possible now with Botsify Chatbot For Website.
Facebook DeepText - Facebook's text understanding engine
ManyChat - ManyChat lets you create a Facebook Messenger bot for marketing, sales and support.
Google Cloud Natural Language API - Natural language API using Google machine learning