HTTP Header Parser Guide
Reference for parsing response headers, duplicate header values, cache directives, CORS signals, MIME clues, and security headers.
Quick answer
Use the HTTP Header Parser to turn copied raw response headers into grouped fields and readable QA notes.
What this tool does
The tool helps inspect cache, CORS, content type, security, duplicate, and indexing-related response headers. It is useful when debugging browser behavior or release issues.
Supported input
- Raw response header text
- Duplicate header names
- Cache-Control values
- CORS headers
- Security headers
- X-Robots-Tag values
Data handling and processing behavior
Processing is handled in the browser for this tool based on the current public implementation. Avoid pasting private cookies, tokens, or authorization headers unless you have reviewed the implementation and your own data handling requirements.
Step-by-step use
- Copy response headers from DevTools, curl, or logs
- Paste the header text
- Review grouped values
- Check cache, CORS, content type, and security notes
- Compare the result with the browser issue you are debugging
Common errors
Pasting request headers for a response issue. Request and response headers serve different roles.
Ignoring status code context. Headers are easier to interpret with URL, method, and status code nearby.
Treating header parsing as live testing. Reproduce the issue in the actual client when possible.
Limits
The parser reads copied text. It does not fetch URLs, inspect live servers, or decide whether a security policy is sufficient.
Next steps
- MIME Type Lookup — compare file extensions with content types
- URL Parser — inspect URL structure and query values
- Meta Robots Tag Generator — prepare X-Robots-Tag style indexing directives