Express is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Polyfill is a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.
React is an open-source JavaScript library for building user interfaces or UI components.