Drupal
https://www.drupal.org/An open source content management system written in PHP utilized to build some of the biggest websites in the world and powers ~2% of all websites on the Internet.
"Come for the software, stay for the community" Drupal is an open source content management platform powering millions of websites and applications. It’s built, used, and supported by an active and diverse community of people around the world. Use Drupal to build everything from personal blogs to enterprise applications. Thousands of add-on modules and designs let people build any site they can imagine. Join us today as we finalize our newest version of Drupal that might change the world! Interested in working on tasks for Drupal? Check out our new contributor documentation for GCI students @ https://www.drupal.org/node/984014
Primary Open Source License: GNU General Public License version 2.0 (GPL-2.0)