Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
AppMockUp - Create the most compelling screenshots for your app.
ioBroker - flexible and modular application for the IoT and Smarthome
Placeit - Generate realistic product shots in seconds
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
Smartmockups - Create stunning product mockups, easily and online.