Jovo - 🗣 Build cross-platform apps for Alexa and Google Home
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
ioBroker - flexible and modular application for the IoT and Smarthome
Voiceflow - Build voice apps in your browser without coding
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation