Cache freshness calculator + policy chooser

Compare a browser max-age with a separate shared-cache s-maxage. This small calculator is intentionally explicit about which lifetime and age it is using.

Freshness calculation

Explicit freshness inputs

Browser max-age / lifetime (seconds) Current age (seconds) Use a separate shared-cache s-maxage

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Policy questions

Describe the response

Response class Personalized or sensitivePublic, changes occasionallyFingerprint/versioned assetMust not be stored May a shared cache / CDN store it? NoYes Are validators available? Yes (ETag or Last-Modified)No Does the request carry Authorization? NoYes Does the body vary by Cookie or user state? NoYes

Educational calculation: this subtracts the supplied age from each supplied lifetime. It omits clock skew, response age calculations, revalidation, stale extensions, browser history/bfcache, service workers, cache partitioning, provider defaults, and hidden cache-key inputs. It is a teaching aid and policy prompt—not a security boundary, proof of storage/reuse, or vendor-specific configuration advice.