Cache & CDN Behavior Checker
Sends 3 identical, sequential requests to the same URL and compares cache-related headers, response bodies, and timing across them.
Based on: RFC 9111 — HTTP Caching
About this validation
Sends a small sequence of repeated requests and compares cache-related headers, response bodies, and timing against RFC 9111's HTTP caching semantics. Reports observed behavior, not a claim about a specific CDN provider.
- Protocol / standard:
- Rules reviewed:
- Sep 1, 2026
Standards and vendor-documented behavior can change. This reflects the source as last reviewed above, not a permanent guarantee.
What This Test Checks
Inspects Age, ETag, Last-Modified, Cache-Control, Expires, Vary, Via, Server-Timing, and common CDN cache-status headers (CF-Cache-Status, X-Cache, X-Cache-Hits, X-Served-By) across 3 sequential requests, then compares response body hash, size, and timing -- the kind of before/after comparison that otherwise needs several manual curl requests.
FAQ
Is a cache MISS a problem?
No. A MISS just means the response wasn't already cached at the time of that specific request -- normal for the first request, or after content changes. This tool reports the observed sequence, not a verdict.
Why does it send 3 requests instead of 1?
A single request can't show caching behavior at all -- you need at least a before/after comparison to see whether a cache is warming up (MISS -> HIT), whether the body stays identical, and whether validators like ETag stay stable.
What does 'ETag changes on every request' mean?
If genuinely identical requests get a different ETag each time, conditional requests and caching based on that ETag stop working -- clients can never get a cache hit because the validator never matches.