Apache is a free and open-source cross-platform web server software.
Endurance Page Cache adds basic file-based caching to WordPress.
Google Sign-In is a secure authentication system that reduces the burden of login for users, by enabling them to sign in with their Google account.
Gravatar is a service for providing globally unique avatars.
Open Graph is a protocol that is used to integrate any web page into the social graph.
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.