ManyChat - ManyChat lets you create a Facebook Messenger bot for marketing, sales and support.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Landbot - An intuitive no-code conversational apps builder that combines the benefits of conversational interface with rich UI elements.
HelpSite - HelpSite is a simple service to help your setup the perfect support centre or help site.
Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
Gist Platform - Live chat, bots & marketing automation -- free.