Rules Presets / Modify Traffic

Modifying API Endpoints

Apart from mapping requests to different host destinations (that return entirely new responses), you can use Fiddler to modify the ongoing traffic by changing API endpoints through their paths, or by changing and substituting parts of the HTTP requests and response headers and bodies.

Creating a "Modify Image Endpoint" Rule

Create a "Modify Image Endpoint" rule by setting the following actions through the Rules Builder.

  1. Create a matching condition that uses the "When all these conditions are met any number of times" pattern.

  2. Match by a URL that uses a string value to match the desired URL. For example, match googlelogo from the following URL https://www.google.com/images/branding/googlelogo/1x/googlelogo_light_color_272x92dp.png.

  3. Match by a Method equal to GET.

  4. Create an Update URL action and set the desired new target URL. For example: https://www.gstatic.com/ac/cb/youtube_logo_v2.svg.

This sample Fiddler rule maps an HTTP request to return a custom image.

Creating "Modify Image Endpoint" rule

Once the rule is created, enable the Rules tab, toggle the rule switch, and start capturing traffic.

Activating the "Modify Image Endpoint" rule

Download a ready-to-use "Modify Image Endpoint" rule as a FARX file, which you can import through the Rules toolbar.

See Also

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