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.
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.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Shopware is an enterprise-level ecommerce platform.
A modest JavaScript framework for the HTML you already have.