How To: Use Fiddler On localhost


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How To: Use Fiddler On localhost

Fiddler Tool is a Web Debugging Proxy, that can help you when recording Web Test for Team System.

IE ,FireFox, Google Chrome and the .NET Framework are hardcoded not to send requests for Localhost through any proxies, and as a proxy, Fiddler will not receive such traffic.

The workaround is to use your machine name as the hostname instead of Localhost or So, for instance, rather than hitting http://localhost:8081/mytestpage.aspx, instead visit http://machinename:8081/mytestpage.aspx. 

…Or, if you’re using Fiddler v2.1.8 or later, just use http://ipv4.fiddler to hit localhost on the IPv4 adapter, or use http://ipv6.fiddler to hit localhost on the IPv6 adapter.  This works especially well with the Visual Studio test webserver (codename: Cassini) because the test server only listens on the IPv4 loopback adapter.

Lastly, you could Customize your Rules file like so:


and add the following rule:

static function OnBeforeRequest(oSession:Fiddler.Session){
(oSession.HostnameIs(“MYAPP”)) { = “”; }

…and then just hit http://myapp, which will act as an alias for

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