HTTP cache freshness calculator

How to use

Estimate HTTP cache freshness remaining from Date, Age, and max-age.

1. Enter the source data or select files.
2. Change only the settings you need.
3. Run the tool, then review, copy, or save the result.

HTTP cache freshness depends on multiple headers

Freshness is influenced by more than Cache-Control max-age: Age, Date, Expires, and shared-cache directives such as s-maxage can also matter. If a CDN and browser behave differently, inspect the complete response headers rather than a single directive. Also remember that no-cache requests revalidation; it does not necessarily prohibit storage.