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CDN Guides

Informational articles about CDN features like Origin Shield and Serve Stale.

CDN Guides are articles packed with information about one CDN feature. The Guide provides generic information, a handy CDN comparison table showing which CDNs support the feature and specifics for each CDN including links to relevant external online resources.

Serve Stale

Serve Stale means the CDN serves expired objects from cache when the origin is down or returns errors. Which CDNs can serve stale?


WebSockets is technology for bidirectional communication in client-server apps. Do all CDNs support proxying WebSockets?


Purging is invalidating or deleting objects in the CDN cache. Which CDNs support purging all objects or purge by tag, key or header?


Prefetching is warming the CDN caches, so first users don't get a slow cache miss response. Which CDNs offer (instant?) prefetching?

Origin Shield

Origin Shield is an extra caching layer between the CDN servers and your origin. Which CDNs have a (paid) Origin Shield?


Compression greatly reduces file size, for faster responses and less bytes over the wire. Do all CDNs support Brotli??