jsDelivr's answer
jsDelivr is the only free CDN that aims to be production ready even for the most critical workloads. It has multiple failover systems for all of its components to ensure 100% uptime and uses multiple CDNs and datacenters for better performance.
cdnjs - An open source community driven JS/CSS CDN.
Bunny.net - BunnyCDN is a simple and powerful CDN, offering lightning fast performance for a fraction of the cost with free SSL, Brotli, HTTP/2 and 100% Pay As You Go pricing.
CloudFlare - Cloudflare is a global network designed to make everything you connect to the Internet secure, private, fast, and reliable.
Amazon CloudFront - Amazon CloudFront is a content delivery web service.
Statically - The free optimization & CDN for images, CSS, JavaScript, and open source.
Amazon AWS - Amazon Web Services offers reliable, scalable, and inexpensive cloud computing services. Free to join, pay only for what you use.