Thunder is web-based, open-source, Drupal 8-based Content Management System (CMS) for professional publishing. Thunder was designed by Hubert Burda Media and released as open-source software under the GNU General Public License in 2016. It consists of the current Drupal 8 functionality, lots of handpicked publisher-centric modules with custom enhancements, and an environment which makes it easy to install, deploy and add new functionality. Everyone can use and enhance the system at no cost. As members of the Thunder Coalition, publishers, industry partners, and developers build custom extensions and share them with the Coalition to further enhance Thunder. Thunder users also benefit from a whole range of channel and feature-specific enhancements through collaboration with industry partners.