Usage of Zend_Json involves using the two public static methods available: Zend_Json::encode() and Zend_Json::decode(). Sometimes, it may be hard to explore JSON data generated by Zend_Json::encode(), since it has no spacing or indentation. In order to make it easier, Zend_Json allows you to pretty-print JSON data in the human-readable format with Zend_Json::prettyPrint(). " ")); } ]]> Second optional argument of Zend_Json::prettyPrint() is an option array. Option indent allows to set indentation string - by default it's a single tab character.