Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Losant - Losant makes building connected experiences and solutions easy.
ioBroker - flexible and modular application for the IoT and Smarthome
Cisco Jasper - Jasper provides a SaaS IoT platform to enable companies of all sizes to launch, manage and monetize IoT services on a global scale.
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
C3 IoT - C3 IoT enables energy companies to realize the full benefit of their IoT and system investments.