Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
Botsify - Ever wonder if you could replace your live chat support system with a chatbot?. Its possible now with Botsify Chatbot For Website.
BotStar - BotStar | Engage Customers Online with Live Chat & Chatbots
Landbot - An intuitive no-code conversational apps builder that combines the benefits of conversational interface with rich UI elements.
Telegram bot API - The Bot API allows you to easily create programs that use Telegram messages for an interface.
ManyChat - ManyChat lets you create a Facebook Messenger bot for marketing, sales and support.