IE9 RC allows fiddler to get localhost calls

March 6, 2011

one comment

For the last couple of days I noticed something odd about my installation of Fiddler – it suddenly started to show me localhost calls when I debugged web applications.

At first I assumed that a new version of Fiddler which I’ve installed recently fixed the oldest problem of fiddler, but apparently it’s not Fiddler who should be given the credit, but rather IE9 RC.

With the new release of IE9 RC, a new ability has been added – proxy loopback traffic.

You can read more about this feature here.


There are several ways to get fiddler to listen to localhost requests, such as changing “localhost” to “localhost.” or to “ipv4.fiddler” which is a special DNS address, but these techniques are workarounds and require some work.

For example if you are debugging a Silverlight application that calls a WCF service, you’ll need to change not the address you are browsing to get the SL application and the WCF address inside the service configuration file, otherwise you will get a cross-domain call to the WCF service which will require you to export a clientAccessPolicy.xml file.

IE9 RC just made things a whole lot simpler now. How wonderful!!

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one comment

  1. Pini DayanMarch 6, 2011 ב 3:35 pm

    You can simply write localhost. (“.”)