Time.is - exact time in any location
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Every Time Zone - Online tool for keeping up with times around the world.
ioBroker - flexible and modular application for the IoT and Smarthome
timeanddate.com - Free Clock for your website or blog!
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation