Apache is a free and open-source cross-platform web server software.
DoubleClick for Publishers (DFP) is a hosted ad serving platform that streamlines your ad management.
Drupal is a free and open-source web content management framework.
Google Publisher Tag (GPT) is an ad tagging library for Google Ad Manager which is used to dynamically build ad requests.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.