Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
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.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.