What you are looking for is called FiddlerCore - http://www.telerik.com/fiddler/fiddlercore. Here is the licensing scheme for FiddlerCore - http://www.telerik.com/purchase/fiddlercore.
Please, feel free to contact me at tsviatko.yovtchev[at]telerik[dot]com if you have any further questions.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items