What is HTTP Header Parser & Explainer?
HTTP response headers are metadata sent by the server alongside the page content. They control caching, security, content handling, CORS access, and redirection. Understanding what each header does is essential for debugging page behavior, optimizing performance, and securing a site. This tool parses raw headers and explains each one in plain English.
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Paste HTTP response headers to get plain-English explanations of each one. Headers are grouped by function (cache, security, CORS, content, redirection). The parser flags missing security headers like HSTS, X-Content-Type-Options, and X-Frame-Options.
limitations
- This parser explains individual headers but cannot verify cross-header consistency or detect all conflicting configurations. Some header interactions require understanding of the full site architecture.
- Header names are not case-sensitive per the HTTP spec, but the parser normalizes to lowercase for matching. Unusual header casing or formatting may cause mismatches.
- Some proprietary or non-standard headers (X- prefixed headers from specific vendors) may not be recognized. The parser groups unrecognized headers under Other.
How to use this tool
- Copy response headers from browser DevTools (Network tab > Response Headers), curl -I output, or server logs.
- Paste them into the text area. The tool parses each header, groups them by function, and explains what each one does.
- Review the security advisories for any missing security headers and follow the next-steps recommendations.
What you can use it for
- Debug why a page is not caching correctly by reviewing the Cache-Control, ETag, and Expires headers.
- Audit a site's security headers to check for missing HSTS, Content-Type-Options, or Frame-Options.
- Understand a third-party API response's CORS headers to debug cross-origin fetch failures.