The CDN listed here (Content Delivery Network) is a free-to-use experience version, for more professional features and services please upgrade the paid version, each of the CDN price is different, not listed. Now let's look at a simple comparison of the various CDN that can be used for free:
Discover that Freecdn (su.zhiduopc.com) is able to provide both DDoS defense, CC defense, and support HTTPS/SSL certificates and unlimited traffic, which is the only one currently found to be able to provide this free service, mostly limiting traffic or not providing DDoS defense/ CC defense, the ability to support HTTPS/SSL certificates is not much.
Application of a use is also good, the background interface concise, easy to operate. Unlimited traffic 1.8T defense, support Pan-resolution + custom https/ssl+ cache acceleration, ignoring CC without human machine verification.
Domestic several free CDN contrast, suits you is the best