HTTP Response Header Analyzer
Inspect server response headers, detect missing security policies (HSTS, CSP, X-Content-Type-Options), evaluate CDN caching rules, and troubleshoot API endpoints.
🔍 HTTP Header Analyzer
Enter a website URL to fetch and analyze its HTTP headers.
Understanding HTTP Response Headers & Security Auditing
HTTP response headers are name-value pairs sent by a web server (e.g. Nginx, Apache, Cloudflare, or AWS CloudFront) to the browser before delivering requested HTML, JSON, or media payloads. Headers instruct browsers how to display content, manage caching lifetimes, handle cross-origin scripts, and enforce strict cryptographic security policies. Auditing headers regularly prevents Cross-Site Scripting (XSS), Clickjacking, MIME-confusion attacks, and accidental caching of sensitive user sessions.
🛡️ Essential Security Headers
- Strict-Transport-Security (HSTS): Forces browsers to connect exclusively over HTTPS, preventing SSL-stripping and man-in-the-middle exploits.
- Content-Security-Policy (CSP): Restricts authorized domains from which scripts, styles, images, and fonts can load, neutralizing modern XSS attacks.
- X-Frame-Options: Controls whether the page can be embedded inside
<iframe>elements, protecting users from Clickjacking. - X-Content-Type-Options: Set to
nosniffto stop browsers from MIME-sniffing files away from declared content types. - Referrer-Policy: Governs how much confidential URL referrer information is transmitted when links are clicked.
⚡ Performance & Caching Headers
- Cache-Control: Dictates caching directives (
public,private,max-age,no-store,immutable) for intermediate proxy caches and browser storage. - ETag (Entity Tag): Unique hash identifier for a specific resource version, enabling
304 Not Modifiedbandwidth savings. - Content-Encoding: Identifies compression algorithms applied to payloads (e.g.,
brfor Brotli,gzip). - Vary: Tells downstream caches which request headers (like
Accept-EncodingorUser-Agent) alter the returned response.
Frequently Asked Questions (FAQs)
fetch() or XMLHttpRequest to an external domain, the browser blocks access to response headers unless that remote server returns Access-Control-Allow-Origin: *. Our analyzer checks headers directly or falls back to public HEAD probes.304 Not Modified status code indicates that the resource has not changed since the timestamp or ETag specified in the client request headers (If-Modified-Since or If-None-Match). The browser reuses its locally cached copy, dramatically accelerating page load times and conserving server bandwidth.add_header X-Frame-Options "SAMEORIGIN" always; and add_header X-Content-Type-Options "nosniff" always; inside your server { ... } block. On Apache, enable mod_headers and declare Header always set X-Frame-Options "SAMEORIGIN" in your .htaccess configuration.Explore Related Tools
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