Apache is a free and open-source cross-platform web server software.
CentOS is a Linux distribution that provides a free, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL).
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Phusion Passenger is a free web server and application server with support for Ruby, Python and Node.js.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.