AngularJS is an open-source JavaScript framework, maintained by Google, that assists with running single-page applications. Its goal is to augment browser-based applications with model–view–controller (MVC) capability, in an effort to make both development and testing easier.
PayPal is a American international e-commerce service that enables companies and individuals to send money and to accept payments without revealing any financial details.
Express is a fast, unopinionated, minimalist web framework for Node.js
Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. It is the preferred encoding for web pages.