Drupal is a free and open-source web content management framework.
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.
Mailchimp is a marketing automation platform and email marketing service.
Open Graph is a protocol that is used to integrate any web page into the social graph.
ShareThis provides free engagement and growth tools (e.g., share buttons, follow buttons, and reaction buttons) for site owners.