Apache is a free and open-source cross-platform web server software.
Gravatar is a service for providing globally unique avatars.
MailChimp for WordPress is an email marketing plugin that enables you to build subscriber lists.
Open Graph is a protocol that is used to integrate any web page into the social graph.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
ShareThis provides free engagement and growth tools (e.g., share buttons, follow buttons, and reaction buttons) for site owners.
WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system.