Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
BotTalk - Create Alexa skills and Google Assistant actions with Markup
Jovo - 🗣 Build cross-platform apps for Alexa and Google Home
Actions on Google - The open platform for Google Assistant
Voiceflow - Build voice apps in your browser without coding
OK Google - Explore over 150 Google Now voice commands in one place