What timezone are dates in API data?

I’m using the card’s id/hash to get extract the creation date. What time zone is this date in? It seems like NY time. But I’m also in NY and want to check it’s not specific to the card-creator/board-creator.

All dates returned by the API are in UTC String ISO8601 format.
But, “due dates” are most of the time set at 12:00 PM in the timezone of the card creator, if the user doesn’t change it.