Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
FHEM - FHEM (TM) is a GPL'd perl server for house automation.
Google Home - Set up, manage, and control your Chromecast, Chromecast Audio and Google Home devices.
Conrad Connect - Service for managing smart home devices
ioBroker - flexible and modular application for the IoT and Smarthome
Homebridge.io - Homebridge is a lightweight NodeJS server you can run on your network that emulates the iOS HomeKit...