[ACCEPTED]-How to display localhost traffic in Fiddler while debugging an ASP.NET application?-web-traffic

Accepted answer
Score: 88

try using this:


instead of


this also works 1 with ports


Here is link to fiddler documentation


Score: 51

To make Fiddler work on localhost with IIS 3 Express you should use this form of URL


This 2 puts correct Host header value (localhost) which 1 satisfies IIS Express.

Score: 20

Start Fiddler. Go to Tools--> Fiddler Options. Choose 3 Connections tab. Check the 'USe PAC Script' option.

Now 2 you will be able to monitor local traffic 1 as well

Score: 12

For an ASP.NET web site project:

1) Right-click 5 the project and select Property Pages
2) Select 4 Start Options
3) Under the Server section, click 3 the "Use custom server" and edit the Base 2 URL by replacing localhost with your computer's 1 name.

Score: 7

Probably the easiest way to monitor traffic 2 to localhost is to replace "localhost" with 1 "localhost." in the browser's URL bar. E.g.

Score: 4

Using Fiddler v4:

  1. Check your IE proxy settings

IE->Tools->Internet Options->Connections->Lan 6 Settings

IE Lan Settings

  1. Check your settings in Fiddler:

Fiddler -> Options-> Connections 5 & Https

Check the Fiddler port, default 4 is 8888 Fiddler port

  1. In Fiddler-Menu:

File -> Capture Traffic is checked

The 3 following solution worked for me, when using 2 a

  • HttpClient or
  • WebClient from inside an ASP.NET application.


                enabled = "true"
                useDefaultCredentials = "true">
      <proxy autoDetect="False" bypassonlocal="False" proxyaddress="" usesystemdefault="False" />


var resourceServerUri = new Uri("http://localhost.fiddler:YourAppServicePort");
var body = c.GetStringAsync(new Uri(resourceServerUri)).Result;

Check if your request actually reaches fiddler by customizing the Fiddler Rules script

Fiddler->Rules->Customize Rules

and 1 hook into the OnBeforeRequest event:

static function OnBeforeRequest(oSession: Session) {

if (oSession.hostname.Contains("localhost:YourPortNumber")

Or explicitly by setting a web proxy

WebClient wc = new WebClient();

WebProxy proxy = new WebProxy();
// try one of these URIs
proxy.Address = new Uri("");
proxy.Address = new Uri("http://hostname:8888");
proxy.Address = new Uri("http://localhost.fiddler");
proxy.Address = new Uri("http://ipv4.fiddler");
// https://en.wikipedia.org/wiki/IPv6
proxy.Address = new Uri("http://ipv6.fiddler");

proxy.BypassProxyOnLocal = false; wc.Proxy = proxy;
var b = wc.DownloadString(new Uri(YourResourceServerBaseAddress));
Score: 3

Check out this link...the 'workaround' is 1 hacky, but it does work:

Tip for using Fiddler on localhost

Score: 3

You may use PC hostname instead of 1 or localhost

Score: 3

Checking the "Use PAC Script" in Fiddler 2 Options -> Connections worked for me when 1 using IIS Express within a corporate intranet.

Score: 2

Ensure that in your Fiddler Connections 2 that localhost isn't in the "IE should bypass 1 Fiddler for URLs that start with:" box.

Score: 2

You should uncheck the checkbox:

Bypass proxy 2 server for local addresses

Located at proxy 1 configuration of Internet Explorer.

Score: 2

Try with <-- note the . at the end

So 3 you can still connect to Casini and debug 2 easily (I'm currently debugging page on 1 ).

Score: 2

One of the possible solutions is remove 2 the proxy settings in IE as follows.

       IE->Tools->Internet Options->Connections->Lan Settings->

disable 1 following

  • Automatically detect settings
  • Use automatic configuration script
Score: 1

If trying to catpure HTTPS traffic on a 3 local machine from BizTalk using Fiddler, try 2 using the WCF Adapter Proxy settings. I 1 used an address of: http://localhost:8888/

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