Bootstrap is a free and open-source front-end framework for designing websites and web applications. It contains HTML and CSS-based design templates for typography, forms, buttons, navigation and other interface components, as well as optional JavaScript extensions.
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript.
MathJax is a cross-browser JavaScript library that displays mathematical notation in web browsers, using MathML, LaTeX and ASCIIMathML markup. MathJax is released as open-source software under the Apache License.
PHP: Hypertext Preprocessor is a server-side scripting language designed for Web development, but also used as a general-purpose programming language. PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management systems, and web frameworks.
Cloudflare Content Delivery Network (CDN) is a geographically distributed group of servers that ensure fast delivery of Internet content, including HTML pages, JavaScript files, stylesheets, and images.
Gmail is a free, advertising-supported email service offered as part of Google's G Suite, with 15GB of storage, color-coded inbox filters and unsend button.
PayPal is a global eCommerce platform for buyers & sellers. PayPal allows payments & money transfers to be made securely via email, phone, text message or Skype.