MessageBird Chat API - Connect with your customers through different messaging apps
Aivo - Skyrocket your Customer Service and Sales KPIs with a Chatbot powered by Artificial Intelligence. Give time back to people.
Voiceflow - Build voice apps in your browser without coding
Zendesk Answer Bot - Chatbots
Twilio Notify - One API to orchestrate notifications across SMS, push & more
Tars - TARS enables users to create chatbots that replaces regular old webforms.