get client machine timezone in asp.net mvc

It will have to be done on the Javascript side, and post that value in a hidden field back to the server. Look into the Date.getTimezoneOffset().

That information is not sent to the server, so there is not trivial way to do it. One option would be to look up the IP in a Geolocation Database. http://www.ip2location.com/ is one.

You can also do a ajax postback using the javascript Date.getTimezoneOffset().

$.get('/User/SetTimeZone' + Date.getTimezoneOffset());

and store this in the session or with the user data.

If you have troubles showing time on the client side then you can do the following I wrote an extension to DateTime class that does conversion for me

public static MvcHtmlString ToClientTime(this DateTime dateTime){
   var builder = new TagBuilder("span");
   builder.MergeAttribute("data-utc-time",dateTime.ToString());
   builder.SetInnerText(string.Format("{0} (UTC)", dateTime.ToString()));
   return new MvcHtmlString(builder.ToString());
}

then I've added a javascript file and let momentjs handle the conversion on the client side

$(document).ready(function() {
  $("[data-utc-time]").text(function () {
    var utcTime = $(this).attr("data-utc-time");
    return moment.utc(utcTime, 'DD.MM.YYYY HH:mm').local().format('DD.MM.YYYY HH:mm');
});