Conrad Connect - Service for managing smart home devices
FHEM - FHEM (TM) is a GPL'd perl server for house automation.
LinHES - ChiliProject
Homebridge.io - Homebridge is a lightweight NodeJS server you can run on your network that emulates the iOS HomeKit...
OpenELEC - OpenELEC, which stands for Open Embedded Linux Entertainment Center, is a Linux operating system that makes the host computer a Kodi media center. The software was the winner of the Swiss Opensource Award in 2014.
pimatic - Home automation framework that runs on node.js.