HTTP Header Checker
Analyze HTTP response headers. Paste headers manually or check what headers your browser sends with requests.
About HTTP Header Checker
Our free HTTP Header Checker helps you analyze HTTP response headers for security, caching, performance, and compliance. HTTP headers contain important metadata about responses including content type, caching policies, security settings, and server information.
Due to browser cross-origin restrictions, most websites cannot be fetched directly from JavaScript. This tool provides two modes: Manual Paste (paste headers from browser dev tools or curl output) and Auto-Detect (shows the request headers your browser sent to load this page).
Understanding HTTP headers is crucial for web developers and security professionals. Security headers like Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security protect against common attacks. Caching headers like Cache-Control and ETag improve performance. This tool highlights security-related headers and provides explanations.
Frequently Asked Questions
Q How do I get HTTP headers from a website?
Open your browser's Developer Tools (F12), go to the Network tab, refresh the page, click on the first request, and look at the Response Headers section. Alternatively, use the command line: curl -I https://example.com to see response headers, or curl -v https://example.com for both request and response headers.
Q What are security headers?
Security headers are HTTP response headers that instruct browsers to enable built-in security mechanisms. Key headers include: Strict-Transport-Security (forces HTTPS), Content-Security-Policy (prevents XSS), X-Frame-Options (prevents clickjacking), X-Content-Type-Options (prevents MIME sniffing), and Referrer-Policy (controls referrer information).
Q Why can't this tool fetch headers directly?
Browser security policies (CORS) prevent JavaScript from making requests to other domains unless the target server explicitly allows it. Most websites don't set the necessary CORS headers for external tools. The manual paste mode works around this limitation by letting you provide the headers yourself.