Intel NUC - Intel NUCs are available as Kits(Barebones), Boards(Mainbaord only) and as perconfigured Mini-PCs.
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Udoo x86 Ultra - Udoo x86 Ultra is a modern PC, known as the most powerful X86 maker board and an Arduino 101 compatible platform.
ioBroker - flexible and modular application for the IoT and Smarthome
Raspberry Pi - The Raspberry Pi is a tiny and affordable computer that you can use to learn programming through fun, practical projects. Join the global Raspberry Pi community.
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation