Amazon Advertising (formerly AMS or Amazon Marketing Services) is a service that works in a similar way to pay-per-click ads on Google.
Google Analytics is a free web analytics service that tracks and reports website traffic.
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.