Browser Cache Header Analyzer
Paste response headers and see whether a resource is fresh, revalidated, or never cached.
Private by design. Every tool runs 100% in your browser — your code, text, and tokens never leave your device. Nothing is uploaded or stored.
Interprets caching directives so you can tell whether a resource is fresh, revalidated, or never cached.
Frequently Asked Questions
What does "fresh" vs "revalidated" mean?
A fresh response is served from cache without contacting the server (Cache-Control max-age). A revalidated one sends a conditional request (ETag/If-Modified-Since) and gets a 304 if unchanged.
Why is my resource never cached?
Common causes: Cache-Control: no-store, a Set-Cookie on the response, or a missing max-age. The analyzer flags which directive is blocking caching.
Should static assets use immutable caching?
Yes — pair Cache-Control: public, max-age=31536000, immutable on versioned filenames (app.4f3a.js) so the browser never revalidates them.