Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
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.
PHP is a general-purpose scripting language used for web development.
RequireJS is a JavaScript library and file loader which manages the dependencies between JavaScript files and in modular programming.