Drupal is considered to be one of the most flexible and feature rich Open Source CMS platforms. It comes with a range of different modules, themes and designs. It is packed with oodles of preconfigured options making it highly customizable. Developed in 1999, Drupal is based on PHP and is mostly used for knowledge management and enterprise applications. Today Drupal boasts of a community of more than 630,000 users and developers worldwide.