Using Fiddler with ASP.NET's default local server

If you've ever done any kind of AJAX debugging, you may have used Fiddler to figure out exactly what is going over the wire.  Fiddler is a neat little tool that let's you analyze the traffic between the browser and the application.  It shows session information, cookies, and a lot more.  One thing that's not clear right away is how to use it with the ASP.NET local server. 

If you run your typical ASP.NET application with the default server, you'll notice that Fiddler is not capturing any traffic.  To remedy this situation, you can simply add a period ('.') to the end of "localhost" in the address bar (http://localhost.:8181/mywebapp).  This will allow you to view your application’s traffic data with Fiddler.

6 Comments

  • Interesting tip, but I get:

    [Fiddler] Connection to localhost. failed.Exception Text: No connection could be made because the target machine actively refused it

  • You might also want to check out this post:
    http://groups.msn.com/HTTPFiddler/bugs.msnw?action=get_message&mview=0&ID_Message=815&LastModified=4675632312984197215

    If you're using Vista, it may have something to do with IPv6 vs. IPv4.

  • Another way around this is to modify your hosts file.

    For Example:
    127.0.0.1 local

    This is not much better than using your computername. The only difference is you won't have to add a rule to allow access on port 80 in your firewall software.

  • To solve the error:
    [Fiddler] Connection to localhost. failed.
    Exception Text: No connection could be made because the target machine actively refused it


    Tools -> Fiddler Options -> remove 'enable IPv6'

  • Not working with asp.net mvc application

  • Can i have a local server in replace of microsoft IIS where i can run my asp.net application.

    Best Regards

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