Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
Aivo - Skyrocket your Customer Service and Sales KPIs with a Chatbot powered by Artificial Intelligence. Give time back to people.
BotStar - BotStar | Engage Customers Online with Live Chat & Chatbots
Zendesk Answer Bot - Chatbots
Telegram bot API - The Bot API allows you to easily create programs that use Telegram messages for an interface.
Tars - TARS enables users to create chatbots that replaces regular old webforms.