Drupal

Drupal is  a free and open source content-management framework written in PHP and distributed under the GNU General Public License. Drupal provides a back-end framework for at least 2.3% of all web sites worldwide – ranging from personal blogs to corporate, political, and government sites. Systems also use Drupal for knowledge management and for business collaboration.

As of January 2018, the Drupal community is composed of more than 1.3 million members, including 109,800 users actively contributing, resulting in more than 39,500 free modules that extend and customize Drupal functionality, over 2,570 free themes that change the look and feel of Drupal, and at least 1,200 free distributions that allow users to quickly and easily set up a complex, use-specific Drupal in fewer steps.