Free HTTP Header Checker - Analyze Request & Response Headers

The UseClick HTTP header checker sends a real network request to any URL you submit and returns the complete set of response headers in a readable, organized view. It captures the status code, every header field the server returned, the response time in milliseconds, and grades critical security headers like Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy. It also extracts caching directives (Cache-Control, ETag, Last-Modified, Expires), server fingerprint headers (Server, X-Powered-By, Via), and detects whether the server is sending compressed responses with gzip, Brotli, deflate, or zstd. You can choose between GET and HEAD requests so you can inspect headers without downloading the response body when bandwidth matters.

HTTP security headers are server-sent instructions that tell browsers how to handle your content securely, and they are one of the cheapest, highest-impact defenses against common web attacks. OWASP recommends a baseline that includes HSTS to force HTTPS, Content-Security-Policy to prevent cross-site scripting, X-Frame-Options or CSP frame-ancestors to stop clickjacking, X-Content-Type-Options to stop MIME sniffing, and a strict Referrer-Policy to prevent URL leakage. A 2024 scan of the Tranco top one million sites found that roughly 75% lacked a proper Strict-Transport-Security header and over 80% had no Content-Security-Policy. Configuring these headers correctly costs nothing in licensing fees but materially reduces the attack surface against XSS, clickjacking, protocol-downgrade attacks, and credential-stealing iframes.

GET and HEAD are both HTTP methods, but they differ in what the server returns. A GET request asks the server for the resource and returns both headers and the full response body, which is how browsers normally load pages and images. A HEAD request asks the server for only the headers without the body, which is faster, uses less bandwidth, and is ideal when you only care about metadata like status codes, caching directives, content length, or security headers. Most servers respond to HEAD with the exact same headers they would send for GET, so our header checker defaults to HEAD for efficiency. However, some misconfigured servers or CDNs handle HEAD differently or return 405 Method Not Allowed, in which case switching to GET in our tool will reveal the real headers.

Our security score ranges from 0 to 100 and weights six critical security headers based on the impact each one has on real-world threat models. Content-Security-Policy and Strict-Transport-Security carry the largest weight because they defend against the highest-frequency attacks (XSS and protocol downgrade). X-Frame-Options and Permissions-Policy receive medium weight for clickjacking and feature-access control. X-Content-Type-Options and Referrer-Policy receive smaller weights because their attack surface is narrower. Each header receives full points when configured correctly, half points when present but weak (for example a short HSTS max-age, a CSP with unsafe-inline, or X-Frame-Options with a value other than DENY or SAMEORIGIN), and zero points when missing. The total is normalized to a 0-100 scale so you can compare different sites or track improvements over time.

Caching headers tell browsers and CDNs whether and how long to store a response so subsequent visits do not require a full download. Cache-Control is the modern directive that defines max-age (in seconds), public versus private storage, s-maxage for shared caches, no-store for sensitive content, and stale-while-revalidate for fast background updates. ETag is a unique fingerprint of the response body, allowing conditional requests where the browser sends If-None-Match and the server replies with a cheap 304 Not Modified if nothing changed. Last-Modified provides a timestamp-based equivalent. Expires is a legacy absolute date that Cache-Control overrides. Correct caching can cut page load times by 50% or more on repeat visits, reduce origin server load, and lower CDN bandwidth costs.

Yes, compression is still one of the highest-leverage performance optimizations available. Brotli typically compresses HTML, CSS, and JavaScript 15-25% better than gzip and is supported by every modern browser. The HTTP Archive 2024 Web Almanac reports that compressed text resources average 70-80% smaller than uncompressed equivalents, which directly translates to faster Time to First Byte, lower Largest Contentful Paint scores, and reduced bandwidth bills. Our header checker reads the Content-Encoding response header to confirm whether your server is actually serving compressed bytes when clients advertise support via Accept-Encoding. If Content-Encoding is missing or set to identity for text responses, you are leaving easy performance and SEO wins on the table.