<form> creditCard: <input type="text" name="creditCard" value="<?php if (isset($_REQUEST['creditCard'])) { echo htmlspecialchars($_REQUEST['creditCard']); } ?> "><br/> <input type="submit"> <input type="hidden" name="go"> </form> <?php include '../infusionsoft.php'; include 'testUtils.php'; if (isset($_REQUEST['go'])) { $out = Infusionsoft_InvoiceService::validateCreditCard($_REQUEST['creditCard']); var_dump($out); }