How to Use the HTTP Header Analyzer
- Paste raw HTTP header text (the part after the request/status line) into the input box. Use the second optional box to compare two responses side by side.
- The analyzer instantly parses every header, categorizes it (CORS, caching, security, encoding) and flags missing or risky directives.
- Review the warnings, compare highlighted differences between the two header sets, and copy the parsed result with one click.
What Is HTTP Header Analyzer?
HTTP headers are key-value pairs sent at the start of every HTTP request and response. They control how browsers and servers communicate: how content is cached, whether cross-origin requests are allowed, how the browser should enforce security, and how payloads are encoded.
Response headers such as Content-Security-Policy, Strict-Transport-Security, X-Content-Type-Options and X-Frame-Options are collectively called security headers. They defend against cross-site scripting (XSS), clickjacking and protocol downgrade attacks. Missing security headers is one of the most common findings in web security audits, and it is exactly what this analyzer surfaces automatically.
CORS headers — Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers and Access-Control-Allow-Credentials — decide whether a browser may read a cross-origin response. Misconfigured CORS (for example reflecting any origin with credentials allowed) is a frequent cause of both broken frontend apps and security holes.
Cache-Control directives like max-age, no-cache, no-store, must-revalidate and public/private determine how long browsers and CDNs keep a resource. A wrong caching policy either wastes bandwidth with repeated revalidations or serves stale content to users.
Analyzing HTTP response headers by hand means reading dense, comma-separated directives and remembering what each one does. This tool normalizes the raw text into a structured report, explains each directive in plain English, compares two environments (for example staging vs production), and points out common misconfigurations immediately.
Common Use Cases
- Debugging CORS errors. Paste the failing response headers to see whether Access-Control-Allow-Origin is present, matches your origin, and conflicts with credentialed requests.
- Security header audits. Quickly check whether HSTS, CSP, X-Frame-Options, X-Content-Type-Options and Referrer-Policy are present on production responses.
- Cache policy verification. Confirm that static assets carry long max-age values while HTML documents revalidate, and catch accidental no-store on cacheable responses.
- Environment comparison. Diff headers between staging and production (or two CDN configurations) with automatic highlighting of added, removed and changed lines.
- SEO & performance reviews. Verify compression (Content-Encoding), redirect chains and canonical-related headers during technical SEO audits.
Frequently Asked Questions
Is the HTTP header analyzer safe for sensitive data?
Yes. All parsing happens locally in your browser with JavaScript. Your header text is never sent to any server, stored, or logged — you can even disconnect from the internet after the page loads.
What header format should I paste?
Paste the plain header block, one "Name: value" pair per line. You can copy it from browser DevTools (Network tab), curl -I output, or a server log. The leading request line (GET / HTTP/1.1) or status line is optional.
Can I compare headers from two different servers?
Absolutely. Paste the first response in the left input and the second in the right input. The tool diffs them line by line and highlights entries that are added, removed or changed, which is ideal for staging-versus-production checks.
Which security headers should every response include?
At minimum: Strict-Transport-Security (HSTS), Content-Security-Policy, X-Content-Type-Options: nosniff, X-Frame-Options (or CSP frame-ancestors), Referrer-Policy and Permissions-Policy. The analyzer marks each one as present or missing.
Does the tool detect CORS misconfiguration?
It checks the common pitfalls: wildcard origin combined with Access-Control-Allow-Credentials: true, missing Access-Control-Allow-Methods on preflight responses, and exposing the response without an Access-Control-Allow-Origin header.