For the Fiddler fans out there, you know how indispensible Fiddler can be in your debugging arsenal.  In case you are not aware, the Fiddler team (Eric Lawerence) released a version for .NET 4.0 back in December that makes using the tool with Windows 8 Metro Apps a Snap (poor attempt at Metro App humor).  Basically they pulled in the completely awesome EnableLoopback Utility Extension.

 

First step, install the .NET Framework v4 version.

The about page should show Version 4.3.9.9 (beta) or better:

 

Next, go to Tools –>Win8 Loopback Exemptions:

 

You may get the following warning, just click OK:

 

You should see a list of all your Metro Apps. Make sure the ones you want to see network traffic for are checked:

 

That’s all there is to it.  Happy hunting!