<model-viewer> is an open-source web component developed by Google and maintained through GitHub. <model-viewer> aims at putting 3D content on the web easily with a few lines of HTML code. This was first introduced with Chrome 72 in July 2019 and enables users to view 3D in the browser and mobile devices.
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.
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.