public String GetRefreshToken(String AuthorizedCode) { string Url = "https://accounts.google.com/o/oauth2/token"; if (RedirectUri == null) { RedirectUri = @"http://localhost"; } string Grant_type = "authorization_code"; string Data = "code={0}&client_id={1}&client_secret={2}&redirect_uri={3}&grant_type={4}"; String Param = String.Format(Data, AuthorizedCode, ClientID, ClientSecret, RedirectUri, Grant_type); String Result = WebUtils.HttpPostResult(Url, Param, WebUtils.ContentType.Form); GoogleTokenData TokenData = JsonConvert.DeserializeObject <GoogleTokenData>(Result); return(TokenData.Refresh_Token); }