Untitled

string nitroUser = @"myUserName";
            string nitroPass = @"MyPass";
            string apiURL = $"https://nitroflare.com/api/v2/getDownloadLink?user={nitroUser}&premiumKey={nitroPass}&file={nitroflareCode}";
            using (WebClient getNitroflareLink = new WebClient())
            {
                getNitroflareLink.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
                string json = getNitroflareLink.DownloadString(apiURL);
                dynamic json_data = JsonConvert.DeserializeObject(json);
                if (json_data.result.recaptchaPublic != null)
                {
                    {
                        string sitekey = json_data.result.recaptchaPublic; // return 6Lenx_USAAAAAF5L1pmTWvWcH73dipAEzNnmNLgy

                        // Load webBrowser
                        string html = $"<html><head><title>reCAPTCHA demo: Simple page</title><script src='https://www.google.com/recaptcha/api.js' async defer></script></head><body><form action='?' method='POST'><div class='g-recaptcha' data-sitekey='{sitekey}'></div><br/><input type='submit' value='Submit'></form></body></html>";
                        webBrowser1.DocumentText = html;
                    }
                }

In any request you might get the following response, and when you do - you should display to the user a Google's ReCAPTCHA v2 using the public key you have received in the response:
{
  "type": "success",
  "result": {
    "recaptchaPublic": "6Lenx_USAAAAAF5L1pmTWvWcH73dipAEzNnmNLgy"
  }
}
After the user completed the ch