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HTTP Cache Header Analyzer

Analyze HTTP cache headers from pasted responses. Check Cache-Control, ETag, Expires, Last-Modified, Vary, Age, CDN cache status, browser caching, and revalidation behavior.

Paste response headers from DevTools, curl, an API response, CDN logs, or a server header dump. The analyzer runs locally in your browser.

Options

Use this to debug browser caching, CDN behavior, stale content, revalidation, and inconsistent cache headers.

Output

HTTP cache analysis output will appear here.
This tool analyzes pasted headers only. Real cache behavior can also depend on browser state, CDN rules, service workers, cookies, authorization headers, and server configuration.

Debugging HTTP Cache Headers Without Guesswork

Caching issues are often hard to see from the page alone. A stale page, repeated API request, missed CDN hit, or broken revalidation flow usually comes down to the response headers.

This HTTP Cache Header Analyzer reads pasted headers and explains how Cache-Control, ETag, Expires, Last-Modified, Vary, Age, and CDN cache status may affect browser and shared cache behavior.

Using the HTTP Cache Header Analyzer

  1. Copy response headers from browser DevTools, curl, an API client, or a CDN log.
  2. Paste the headers into the analyzer.
  3. Choose the resource type, such as HTML, API, static asset, or image.
  4. Review TTL, cacheability, revalidation, CDN status, and warnings.
  5. Copy the summary, report, JSON, Markdown, or CSV output.

Common Cache Header Problems

  • no-store prevents browser and shared caching entirely.
  • HTML pages with very long max-age can serve stale content after deploys.
  • Missing ETag or Last-Modified can make revalidation less efficient.
  • Vary: * makes caching difficult or impossible for many caches.
  • Conflicting Expires and Cache-Control headers can confuse debugging.
  • CDN cache status headers may show MISS, BYPASS, EXPIRED, STALE, or HIT behavior.

Example Cache-Control Header

Cache-Control: public, max-age=3600, stale-while-revalidate=86400
ETag: "a1b2c3d4"
Vary: Accept-Encoding

Different Resources Need Different Cache Rules

A fingerprinted JavaScript file can often be cached for a long time. An HTML document usually needs shorter caching or revalidation. API responses depend on whether they are public, personalized, authenticated, or frequently updated.

Always review caching based on the resource type and user impact instead of applying one rule to every response.

Frequently Asked Questions

What does an HTTP Cache Header Analyzer do?

It reads pasted response headers and explains browser cache, CDN cache, TTL, revalidation, and risky cache patterns.

Does this tool fetch a live URL?

No. It only analyzes the headers you paste into the browser.

What is the difference between max-age and s-maxage?

max-age controls browser and cache freshness, while s-maxage applies to shared caches such as CDNs and proxies.

Should HTML pages be cached?

They can be cached carefully, but long HTML cache times can cause stale content after deploys.

Is anything uploaded when I analyze headers?

No. The analysis runs directly in your browser.