Knowledge in PHP , MySQL , Ajax / JavaScript , HTML / CSS & JQuery is must.
Plug - in and other major criteria also having great hand on Core PHP and Oops concepts.
Sound Knowledge in developing complex applications using PHP MVC frameworks OOPS Concepts.
Knowledge of CodeIgniter & Other Frameworks like CakePHP , Laravel , Symfony or Yii will be added advantage.
Knowledge of Magento / Moodle , Joomla , Drupal will added advantage.
Git / SVN , Angular , Node , MongoDB