HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Imperva is a cyber security software and services company for networking, data, and application security.
Polyfill is a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Typekit is an online service which offers a subscription library of fonts.