Braintree, a division of PayPal, specializes in mobile and web payment systems for ecommerce companies. Braintree provides clients with a merchant account and a payment gateway.
Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.