Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
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.
Plesk is a web hosting and server data centre automation software with a control panel developed for Linux and Windows-based retail hosting service providers.
Shopware is an enterprise-level ecommerce platform.
A modest JavaScript framework for the HTML you already have.