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.
Yandex CDN - Разработчики сайтов могут загружать различные JavaScript-фреймворки и библиотеки с открытым исходным кодом с серверов Яндекса по постоянным ссылкам.
CloudFlare - Cloudflare is a global network designed to make everything you connect to the Internet secure, private, fast, and reliable.
Google Hosted Libraries - A stable, reliable, high-speed, globally available content distribution network for the most popular open-source JavaScript libraries.
KeyCDN - KeyCDN is a high-performance Content Delivery Network (CDN). Lowest price globally at $0.04/GB with HTTP/2 Support and free Origin Shield.
Statically - The free optimization & CDN for images, CSS, JavaScript, and open source.