Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Open Graph is a protocol that is used to integrate any web page into the social graph.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.
A modest JavaScript framework for the HTML you already have.
Typekit is an online service which offers a subscription library of fonts.