Today we’re excited to announce Cache Response Rules. These are a new rule type that runs after an origin server replies but before Cloudflare caches the content.
If you've ever been irked watching something that should easily sail out of cache get dragged back to the origin by a stray Set-Cookie or wrong Cache-Control, headers that are sometimes hard or impossible to strip or change on the origin itself, then Cache Response Rules is that fix, applied at exactly the right moment.
When and how caching decisions are made
A CDN cache and an origin server work as a pair. Their goal is to answer from the cache whenever possible and only go back to the origin when the edge can’t respond. Every point of cache hit ratio comes from getting that division of labor right. Check the cache when we shouldn't, and we waste a lookup that was always going to miss. Check it too rarely, the origin serves traffic the edge should have absorbed, and the performance win evaporates.
Importantly, the origin guides the cache. When it returns a cacheable asset, its response headers tell Cloudflare how long it’s OK to serve it, when and how to revalidate, and even whether to cache it at all. The cache is only ever as efficient as the origin allows. If the origin gets it wrong, cache becomes decoration while the origin infrastructure costs skyrocket.
Most cache eligibility problems are not decided at request time. They manifest after the origin replies.
A visitor asks for /static/app.js. Cloudflare checks cache, it misses, and forwards the request to the origin. The origin returns the file. Somewhere in those response headers, quietly, is a Set-Cookie header. The asset that should have been cached at every Cloudflare data center is now uncacheable. Multiply that by every visitor, on every site, with the same accidental header, and you have a cache hit ratio that is leaking origin bandwidth, ruining performance, and driving infrastructure costs higher.
There is a long list of variations of this same problem. The origin sends Cache-Control: no-cache on assets that are perfectly safe to cache on the CDN. The origin sends correct directives, but they're meant for the browser, not for Cloudflare. Or the origin attaches an ETag (an identifier for a specific version of a resource) that's overly agg
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Source: Cloudflare Blog (Published: Thu, 23 Jul 2026 18:40:38 GMT). Read the full article on the original site.
