How to use HTTP Cache Freshness Simulator
- Paste the observed response headers and enter request, response and reuse times in UTC.
- Select a shared or private cache and supply authorization and Vary assumptions.
- Read age, lifetime and storage/validation observations together before exporting.
Example: HTTP Cache Freshness Simulator
Calculate current cache age and explicit freshness from supplied response headers and ordered UTC scenario times.
Options
- Cache kind
- Shared caches use s-maxage when present; private caches use the applicable max-age or Expires evidence.
- Vary matching
- A fresh age does not establish request-field matching. Enter a match only when the required request evidence supports it.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
Freshness and permission to reuse are separate
The age calculation accounts for response delay and time spent in the cache. no-store, private, authorization, Vary and no-cache can restrict storage or reuse even while an explicit lifetime remains. Missing Date or freshness evidence stays unknown instead of receiving a guessed heuristic lifetime.
Questions about HTTP Cache Freshness Simulator
Does a fresh result guarantee reuse?
No. Review the separate storage, validation and Vary observations.
What if Date is unavailable?
Exact current age remains unknown in this selected model.
Are stale responses always forbidden?
This report does not model every stale extension or request permission; it identifies the stated restrictions.