PHPTester.net - PHPTester.net gives developers and learners the ability to write their PHP code and get the output online.
CodeLobster PHP Edition - CodeLobster - Free portable PHP IDE with support Drupal, Smarty, Twig, WordPress, Joomla, JQuery, CodeIgniter, HTML, CSS, JavaScript, AngularJS, CakePHP, Facebook, Laravel, Phalcon, Symfony, Yii
WritePHPOnline.Com - WritePHPOnline.Com is an online site that enables you to write code in PHP and view its output.
Kodiak PHP - Kodiak PHP can run any PHP code directly (offline) on your iPad, no need for an internet connection.
OnlinePHPFunctions - OnlinePHPFunctions is a powerful online code tester that lets you add PHP source code and view its output on your favorite web browser.
Paiza.io - Paiza.io allows you to write and run code in many languages.