        contentType: "application/x-www-form-urlencoded", // set the request Content-Type header
                dataType : 'json', // data type
                data : $("#signup_form").serialize(), // post data || get data
                success: function(data, status){
                    alert("Server response data: " + JSON.stringify(data) + "\nStatus: " + status);
                },
                error: function() {
                    alert("Username already taken");
                }
            }