Free Online HTTP Header Parser
Parse and analyze HTTP request or response headers online. Categorizes headers, checks for missing security headers, and explains each field — free, 100% client-side.
100% Client-Side · Your data never leaves your browserHow to Use HTTP Header Parser
Paste raw HTTP headers (copied from browser DevTools, curl -I, or a proxy tool) into the input area, then click Parse or press Ctrl/Cmd+Enter.
- You can include the HTTP status line (e.g.
HTTP/2 200 OK) — it will be ignored automatically. - The results table shows each header's name, value, category, and description.
- The Security Score badge counts how many of the 6 recommended security headers are present.
- The Security Header Checklist shows which security headers are present (green) and which are missing (red).
- Amber warnings appear for deprecated headers like
X-XSS-Protection. - Use Export JSON to download the parsed headers as a JSON file.
Frequently Asked Questions
What are HTTP headers?
HTTP headers are key-value pairs sent at the start of every HTTP request and response. They convey metadata such as content type, caching rules, authentication details, CORS policies, and security directives between clients (browsers) and servers.
Why do security headers matter?
Security headers instruct browsers to apply protective behaviors. For example, Content-Security-Policy prevents XSS attacks, Strict-Transport-Security enforces HTTPS, X-Frame-Options prevents clickjacking, and X-Content-Type-Options stops MIME-type sniffing. Missing security headers are one of the most common findings in security audits.
What are CORS headers and why do they matter?
CORS (Cross-Origin Resource Sharing) headers control which external origins can access your API or resources. Access-Control-Allow-Origin tells the browser which origins are permitted. Misconfigured CORS headers are a common source of security vulnerabilities and frontend bugs.
What do caching headers do?
Caching headers like Cache-Control, ETag, and Last-Modified tell browsers and CDNs how long to cache a resource and how to validate stale copies. Correct caching headers reduce server load and improve page load speed for returning visitors.
How can I view a website's HTTP headers?
Open browser DevTools (F12), go to the Network tab, reload the page, click any request, and look at the "Response Headers" section. Alternatively, run <code>curl -I https://example.com</code> in the terminal, or use proxy tools like Charles or Fiddler.
Is my data private when using this tool?
Yes. All parsing runs in your browser using JavaScript string processing — nothing is sent to any server. You can safely paste headers from internal APIs, staging environments, or sensitive endpoints.