Those of us used to the SharePoint 2010 interface should be familiar with the Sign in as Different User option. It was a great feature that helped immensely with troubleshooting and developing in SharePoint.
Low and behold, in SharePoint 2013, this feature is gone. Of course, if you’ve installed 2013, you already knew this. This is old (OOOOOLLLLLDDDDD) news. What might not be old news, is there is a simple way to force SharePoint to allow you to still use the feature. Here it is, in all it’s glory.
On any URL in your SharePoint farm, add the following to the end of the URL.
So your URL will look like this: http://<URL>/_layouts/closeConnection.aspx?loginasanotheruser=true
You’ll then be presented the standard windows authentication box. Go ahead and login as your different user and you’re ready to go.
**WARNING** It seems the feature must have been removed due to caching issues. In testing on my own, I found Logging out using the SharePoint Interface or even closing the Browser tab does not clear the “different” user credentials, thus it is possible for the user who owns the Windows session to still be able to access a SharePoint site as the new account. Even after they have logged back in as themselves. The only remedy for this seems to be to close the browser itself. Even clearing the cache doesn’t always do it.
Be careful using this option. A better way might be to simply run Internet Explorer as yourself, then close when your’e done. Using the above method, though is a great way to test if there are issues with the users profile or settings in the profile such as Internet Explorer settings.
I hope this helps someone.