I need to be able to modify the HTTP headers for Internet Explorer for testing purposes.
Basically, I want to achieve the exact same thing that the Modify Headers p
To modify the header with Fiddler:
1- Open Fiddler Web Debugger and in the menu toolbar go to Rules->Customize Rules... (shortcut is Ctrl + R). It opens the CustomRules.js file. Fiddler may suggest you to download Fiddler ScriptEditor but you can edit it with any text editor (I use notepad++)
2- Find OnBeforeRequest(oSession: Session) in the script file.
3- You can add a new header by adding oSession.oRequest["NewHeaderName"] = "New header value"; to OnBeforeRequest function. Also, to remove a header, use oSession.oResponse.headers.Remove("HeaderName"); function.
For more information see this link