Despite the accepted answer that states all times are UTC on SE, it's clear that some times are relative and that chat time stamps reflect local time zones other than UTC.

Chat and iOS apps seem to localize time for me.

What parts of the Stack Exchange use time zone offsets that could be other than UTC to render times visible to end users and how is the Time Zone established for each such place?

  • AFAIK nothing uses a local time – psubsee2003 Dec 29 '13 at 15:44
  • @psubsee2003 Chat uses Time Zone as opposed to relative times or UTC times and I would like to know how that works. – bmike Dec 29 '13 at 15:44

With the exception of chat (which is a fact I just used today), all of the precise time stamps are based on UTC time.

The relative times that you see (such as "yesterday", "2 days ago", etc) are just that, relative based on 24 hour periods from the current moment, so there is no time zones taken into account. For example, a question asked 23 hours ago, regardless of date, is labeled as 23 hours ago. Where a question asked 25 hours ago is labeled as yesterday.

So chat is the only place where any time localization is occurring.

And based on Why does the Transcript and the actual chat room have different Timestamps?, the time localization only occurs in the user interface. Downloading transcripts shows the actual UTC timestamp.

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Actually I was just able to confirm the "UTC Time" we see when opening the Achievements box (previously displayed when hovering our display name in the old top bar) is based on local machine time:

(screenshot was taken NOW, 16:01 UTC time and I just changed my local time)

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  • Did you change your system time? Or your timezone? Seems to be a bug if you ask me – psubsee2003 Dec 29 '13 at 16:14
  • @psubsee2003 yes, mentioned this in the end of my post. It also caused SO to get a black theme (background of answers became black) but reloading resolved it. – Shadow Wizard Wearing Mask Dec 29 '13 at 16:14
  • Reason I asked is I can't repo it... I changed my time and it still displays the same (correct) UTC time – psubsee2003 Dec 29 '13 at 16:21
  • @psubsee2003 try hard refresh, clearing your cache etc. – Shadow Wizard Wearing Mask Dec 29 '13 at 16:24
  • still nothing... I tried another browser that I never use as well. Huh, I wonder if this might be localized to specific browsers or OS's? – psubsee2003 Dec 29 '13 at 16:34
  • @psubsee2003 hmm... will have to try again at some point but screenshot proves it happened. :) – Shadow Wizard Wearing Mask Dec 29 '13 at 16:36
  • Don't doubt it happened, but seems to be a specific set of circumstances. – psubsee2003 Dec 29 '13 at 16:40

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