cdnjs is a free distributed JS library delivery service.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
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.
MDBootstrap (Material Design for Bootstrap) is a complete UI package that can be integrated with other frameworks such as Angular, React, Vue, etc. It is used to design a fully responsive and mobile-friendly layout using various components, plugins, animation.