Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
RackCache is a quick drop-in component to enable HTTP caching for Rack-based applications.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.