Dialogflow - Conversational UX Platform. (ex API.ai)
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Octane AI - Octane AI offers tools to create a bot and engage customers and audience via messaging.
Twilio Flex - The programmable contact center platform 📱
Botkit - Botkit is an open source developer tool for building chat bots, apps and custom integrations for major messaging platforms.
Drift - A messaging app that helps you grow your business.