Replace JSON properties in HTTP response using Fiddler and JSON.NET

FiddlerResponseJsonReplace.cs

// Make sure to add references to Newtonsoft.Json.dll and System.Core.dll into Tools\Options\Scripting\References
// e.g., C:\Windows\Microsoft.NET\Framework64\v4.0.30319\System.Core.dll;C:\Users\username\AppData\Local\Programs\Fiddler\Newtonsoft.Json.dll
public static void OnBeforeResponse(Session oSession)
{
    if (m_Hide304s && oSession.responseCode == 304)
    {
        oSession["ui-hide"] = "true";
    }

    if (oSession.oRequest.host == "www.myhost.com" &&
        oSession.url.Contains("/My/Api")) {

        // FiddlerObject.log("Api matched!");

        oSession.utilDecodeResponse();
        var responseString = System.Text.Encoding.UTF8.GetString(oSession.ResponseBody);

        JObject parsed = JObject.Parse(responseString);

        // Replace the value of tokens named "token" at all levels.
        foreach (JToken token in parsed.SelectTokens("$..tokens"))
        {
            JProperty jProperty = token.Parent as JProperty;
            if (jProperty != null)
            {
                jProperty.Value = "changed";
            }
        }

        string transformed = parsed.ToString();
        oSession.ResponseBody = System.Text.Encoding.UTF8.GetBytes(transformed);

        // FiddlerObject.log(transformed);
    }

}