HTTP headers are the hidden metadata exchanged between browsers and servers with every web request. Our HTTP headers checker reveals all response headers for any URL, helping developers debug issues and security professionals audit configurations.
What HTTP Headers Reveal
Headers contain crucial information about how content should be handled: caching policies, content type and encoding, server software, security settings, and custom application data. Understanding headers is essential for web development and troubleshooting.
Important Security Headers
Modern websites should implement these security headers:
- Content-Security-Policy (CSP) - Controls which resources can load
- X-Frame-Options - Prevents clickjacking attacks
- Strict-Transport-Security (HSTS) - Enforces HTTPS
- X-Content-Type-Options - Prevents MIME sniffing
- X-XSS-Protection - Enables browser XSS filtering
Caching Headers
Caching headers like Cache-Control, Expires, ETag, and Last-Modified determine how browsers store and revalidate content. Proper caching dramatically improves site performance by reducing server requests and load times for returning visitors.
Debugging with Headers
When troubleshooting website issues, headers provide valuable clues. Check Server and X-Powered-By to identify the server stack, Content-Type for MIME issues, Content-Encoding for compression status, and Set-Cookie for session problems.
Use Cases
Developers use header checks to verify CDN configuration, test CORS settings, debug caching issues, audit security posture, and ensure proper content negotiation. It's an essential tool for web professionals.