Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
BotTalk - Create Alexa skills and Google Assistant actions with Markup
Botsify - Ever wonder if you could replace your live chat support system with a chatbot?. Its possible now with Botsify Chatbot For Website.
OK Google - Explore over 150 Google Now voice commands in one place
ManyChat - ManyChat lets you create a Facebook Messenger bot for marketing, sales and support.