ioBroker - flexible and modular application for the IoT and Smarthome
PiDome.org - PiDome is the Home Automation Platform for the Raspberry Pi containing a server, multiple clients with user friendly interfaces
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
MyController.org - MyController.org is an IoT automation controller for home, office or any place.
Domoticz - Domoticz is a lightweight Home Automation System
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation