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.