Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
Jovo - 🗣 Build cross-platform apps for Alexa and Google Home
Actions on Google - The open platform for Google Assistant
API to bot - Convert your API to Alexa skill or Google Home app in 5 mins
Voiceflow - Build voice apps in your browser without coding
Subcast - Podcasts as simple as radio.