How to use a different proxy for some sites and fiddler Classic for others

Environment

Description

In some cases, when using Fiddler Classic it may be necessary to allow traffic through to an upstream proxy. If this is needed, follow the below solution.

Solution

1. Configure the OS Auto Proxy settings with a PAC file and with Fiddler's Proxy configuration.

   

2. Use a catch in the PAC file.

function FindProxyForURL(url,host){

    // Catch specific URL
    if (shExpMatch(url,"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx")){
        return "PROXY xxxxxxxxxxxxxx";
    }

    // Let other URLs use fiddler
    return "PROXY localhost:8888";
}

3. Start Fiddler Classic with -noattach flag.

fiddler.exe -noattach

4. Set Fiddler Classic Gateway Options to No Proxy to prevent infinite loop.