ioBroker - flexible and modular application for the IoT and Smarthome
EventGhost - EventGhost is an advanced, easy to use and extensible automation tool for MS Windows.
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Homeseer - HomeSeer presents a revolutionary approach to home automation.
Domoticz - Domoticz is a lightweight Home Automation System
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation