Apache is a free and open-source cross-platform web server software.
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.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.
Ubuntu is a free and open-source operating system on Linux for the enterprise server, desktop, cloud, and IoT.