I didn't even know that was possible...
Welcome to the rabbit hole that is date/time handling.
Yup. Probably just step lightly out of that one. Already have too many irons in the fire
Here there is no time...
Re:Show HN: An easy way to convert time
by TazeTSchnitzel on Thursday June 29, 2017 @06:58PM
(#14667516)
Is this using a proper date/time library underneath, or did you write it yourself?
moment.js mostly
https://api.epoch.sh/2016-12-31T23:59:60Z
Edge case, but 2016-12-31T23:59:60Z is a valid UTC time.