HTTP headers lookup

Free HTTP Headers Lookup — See Every Header a URL Returns

This tool sends a standard GET request to any URL and shows you every HTTP response header the server sends back — status code, content type, caching directives, security headers, compression, server software and more. Enter a URL and you get the full conversation between server and browser that's normally invisible.

Headers control a surprising amount of how a page behaves and ranks. Cache-Control and Expires headers decide whether returning visitors re-download assets or load them instantly. Content-Encoding shows whether compression (Gzip or Brotli) is active. Security headers like Strict-Transport-Security, X-Content-Type-Options and Content-Security-Policy protect your users and signal a well-configured site. And the status code confirms whether a URL truly returns 200, redirects, or quietly serves an error.

Use this tool to verify caching is set correctly (a major speed win), to confirm compression is enabled, to audit your security headers, to check that redirects return the right status, and to debug why a page behaves differently than expected. For developers and SEOs alike, the response headers are where many invisible problems — and many easy performance wins — are hiding.

From one check to a complete audit

This tool checks one thing. Smart SEO Audit checks 50+ — technical, on-page, content and speed — on any URL in under 10 seconds, with an AI-prioritized fix list, scheduled monitoring and Swiss, GDPR-compliant hosting. Start free — 5 full audits a month, no credit card.