Developer Utilities

Cache-Control Parser & Builder

Parse, normalize, and check HTTP Cache-Control directives.

What the Cache-Control tool checks

The parser separates comma-delimited directives without splitting commas inside quoted values, normalizes directive names, removes duplicate names in the formatted output, and warns about common conflicts such as public with private or non-numeric freshness values.

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Operational limits

  • Cache-Control semantics differ between requests and responses; the presets are response-oriented examples.
  • A valid header does not override every CDN rule, surrogate header, framework cache, service worker, browser heuristic, or explicit purge.
  • immutable is most appropriate for versioned resources whose URL changes whenever content changes.
  • Do not cache personalized or sensitive responses publicly without a complete review of authentication, Vary, cookies, and intermediary behavior.

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How to Use Cache-Control Parser & Builder

  1. Paste a Cache-Control header value or choose a response-oriented preset.
  2. Review the parsed directives, normalized header, and any conflict warnings.
  3. Adjust directive values for the origin and cache architecture you actually use.
  4. Verify the deployed response headers and cache behavior after publishing.

Frequently Asked Questions

What is the difference between no-cache and no-store?

no-cache allows a stored response but requires validation before reuse. no-store tells caches not to store the response. They are not interchangeable.

What does s-maxage control?

s-maxage sets freshness for shared caches and takes precedence over max-age there. Browser and private-cache behavior can still differ.

Can this tool guarantee CDN behavior?

No. It validates syntax and flags common conflicts, but actual behavior depends on the complete response, request directives, cache implementation, CDN policy, framework defaults, and invalidation state.

Sources & references

Primary references: RFC 9111: HTTP Caching; RFC 9110: HTTP Semantics.

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