@the_robogram All time and timezone data is provided by your browser and system clock. I tried to keep the code as simple as possible to present this as useful information through the UI. So generally things should either be pretty darn accurate, or way off (if I happen to push a bug somewhere :). If you notice anything imperfect, please do let me know!
Edit: Actually I realized there are a couple pieces of data I added to supplement what's provided by the browser. These are niceties, and not used to calculate any actual times. So while I wouldn't launch a rocket based off of this site, it should be fine for 99.99% of users' needs.
TimeInZone
klemmbrett – early access