PlaReact Content Loader allows you to create your animated skeleton-screen components giving a wireframe of your pages like placeholder boxes for content and images. Supports React, React Native, Vue, and vanilla HTML.
UI Ball Loaders
UI Ball Loaders offer free loaders & spinners for your next project. Built with HTML, CSS, and SVG. Available for React and copypasta.
CSS Loaders by FreeFrontend
FreeFrontend site collected 150+ great animated preloaders writing in HTML and CSS, all from Codepen.