Determine user's local timezone

Hi,

I have a set of UTC timestamps that I would like to present to users in their browsers’ respective timezones (not deployment server’s timezone). Is there a way to go about this which doesn’t involve geolocating their IP addresses?

Thanks in advance!

I guess How can I get the IP of an incoming request? is a similar type of question - how can we get information of the user querying our app?