HTTP Header Diff Tool

HTTP headers control caching, security, CORS, content type, and more. When debugging or deploying, headers often differ between staging and production, or between different API versions. A header diff tool lets you quickly spot differences: missing security headers, changed cache policies, or CORS misconfigurations. Compare two responses side by side to find what changed.

Headers only in Set A appear in red — they're missing from B. Headers only in Set B appear in red — they're new in B. Headers in both with identical values appear in green — no change. Headers in both with different values appear in yellow, with both values shown — these are the ones to investigate. The counts (total A, total B, matching, different, unique to each) give you a quick summary.

Compare staging vs production API responses to ensure headers match. Verify security headers (CSP, HSTS, X-Frame-Options) are present in production. Check cache headers (Cache-Control, ETag) between environments. Debug CORS by comparing Access-Control-* headers. Validate that a CDN or proxy isn't stripping or altering headers.