How do I get Fiddler to stop ignoring traffic to localhost?

Question

To get Fiddler to capture traffic when you are debugging on local host, after you hit F5 to begin degugging change the address so that localhost has a "." after it.

For instance, you start debugging and the you have the following URL in the Address bar:

http://localhost:49573/Default.aspx

Change it to:

http://localhost.:49573/Default.aspx

Hit enter and Fidder will start picking up your traffic.

Fiddler's website addresses this question directly.

There are several suggested workarounds, but the most straightforward is simply to use the machine name rather than "localhost" or "127.0.0.1":

http://machinename/mytestpage.aspx

The correct answer is that it's not that Fiddler ignores traffic targeted at Localhost, but rather that most applications are hardcoded to bypass proxies (of which Fiddler is one) for requests targeted to localhost.

Hence, the various workarounds available: http://fiddler2.com/documentation/Configure-Fiddler/Tasks/MonitorLocalTraffic

Fiddler v4.5.1.0 will allow you to go to replace "localhost" with "localhost.fiddler", and present localhost as the host name for the receiving server running on your machine.

This avoids "host not recognised" errors when connecting to WCF services with the built in web server that visual studio uses.

i.e. Instead of http://localhost:51900/service.wcf you can use http://localhost.fiddler:51900/service.wcf

Internet Explorer has a new feature since IE9 RC: adding <-loopback> to the proxy bypass list causes WinInet (the network library used by IE) to send requests destined for localhost and 127.0.0.1 through the defined proxy.

Here's the original announcement by @EricLaw: http://blogs.msdn.com/b/fiddler/archive/2011/02/10/fiddler-is-better-with-internet-explorer-9.aspx

For Fiddler to capture traffic from localhost on local IIS, there are 3 steps (It worked on my computer):

1. Click Tools > Fiddler Options. Ensure Allow remote clients to connect is checked. Close Fiddler.

2. Create a new DWORD named ReverseProxyForPort inside KEY_CURRENT_USER\SOFTWARE\Microsoft\Fiddler2. Set the DWORD to port 80 (choose decimal here). Restart Fiddler.

3. Add port 8888 to the addresses defined in your client. For example localhost:8888/MyService/WebAPI/v1/