To do that you have to use windows integrated authentication, provided by IIS (included in windows server). So that is possible but is a bit convoluted. You need an IIS server, a folder with WIA on, and then make a request to a file in that folder. Then this file must have code (eg a .ashx file in C#) to identify the user and return that info to the browser. So you see, it’s a lot of steps just to get the windows user. And an authentication window could pop up if the user hasn’t logged in into that server before…