Creator here. ZoneYrd is a side project I've been sporadically working on over the past years. I often needed to know what time it is in some other place in the world and compare those times on a specific date and time. You can create multiple comparisons at the same time. We store them in cookies, so when you visit the page the next time, everything is as you left. Tech stack is:

  * AngularJS (I started this project before Angular v2 was released)
  * Firebase for hosting/analytics/short links
  * Google Maps for searching for cities

I'm happy to answer any questions.