Free HTTP Header Checker - Analyze Request & Response Headers
Paste any URL to instantly analyze its HTTP headers. See security headers, caching directives, cookies, CORS policies, and more. Debug performance and SEO issues fast.
Last updated: May 2026
HTTP Header Analyzer
Enter a full URL including https://
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- Status Code and Response Time
- Security Headers
- Cache-Control, ETag, Last-Modified
- Server, X-Powered-By, Via
- gzip / Brotli compression detection
Header Analysis Results
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What Are HTTP Headers?
HTTP headers are key-value pairs sent between a web browser (or client) and a web server during a request-response cycle. They carry metadata about the request or response - like content type, caching rules, authentication tokens, security policies, and more. Our HTTP Header Checker tool lets you inspect these headers for any URL, helping you debug issues, verify security configurations, and understand how websites handle your data.
Why Security Headers Matter
Security headers can reveal risks and performance issues on the modern web.
Check Security
Verify whether important security headers like CSP, HSTS, and X-Frame-Options are present. Missing headers can create vulnerabilities.
HSTS and similar headers block basic attacks
Performance
Headers like Cache-Control and Compression can strongly influence performance. Optimize them for faster load times.
XSS has stayed among OWASP's top risks for years
Troubleshooting
Sometimes the problem is in header configuration. Quickly identify missing or incorrect headers.
Clickjacking hits banks, social networks, and SaaS dashboards
Stop MIME Confusion
X-Content-Type-Options: nosniff tells the browser to trust the Content-Type the server declared and not try to guess. Without this header, an attacker who can upload a file labeled as an image can sometimes get the browser to execute it as JavaScript.
One line of config blocks an entire attack class
Protect Privacy with Referrer-Policy
Referrer-Policy controls how much URL data the browser leaks to other origins when users click outbound links. A strict policy like strict-origin-when-cross-origin prevents sensitive query parameters, session tokens, or internal admin paths from leaking to third-party analytics and ad networks.
GDPR and CCPA actively penalize accidental data leakage
Lock Down Browser APIs with Permissions-Policy
Permissions-Policy (formerly Feature-Policy) restricts which browser APIs your origin and embedded iframes can access. Disabling camera, microphone, geolocation, and payment APIs you do not use eliminates entire categories of supply-chain and third-party exploit risk.
Minimize the API surface attackers can reach
Performance Headers Explained
Caching and compression headers can make a site feel 5x faster with no code changes. Here is how the most important ones work.
Cache-Control
The modern caching directive. Use max-age=31536000, immutable for fingerprinted static assets, private, no-store for sensitive responses, and s-maxage for CDN-only TTLs. Correct Cache-Control alone can cut repeat-visit load times by 50-90%.
ETag & Last-Modified
Validators that enable conditional GET requests. When set, the browser sends If-None-Match or If-Modified-Since and the server replies with a cheap 304 Not Modified instead of resending the full body, saving bandwidth without losing freshness.
Content-Encoding (gzip / Brotli)
Brotli compresses text 15-25% better than gzip and is supported by every modern browser. The HTTP Archive reports compressed text averages 70-80% smaller than uncompressed, directly improving Core Web Vitals like Largest Contentful Paint and First Contentful Paint.
Vary
Tells caches that the response depends on certain request headers (commonly Accept-Encoding or Accept-Language). Setting Vary correctly prevents a CDN from serving a gzip-only response to a client that does not support gzip, which would otherwise break the page.
Age & X-Cache
The Age header reveals how many seconds a CDN has been holding the response. X-Cache (set by many CDNs) tells you whether you got a HIT or MISS. Together they verify your edge caching is actually working in production.
Common HTTP Header Issues
These are the most frequent header misconfigurations we see when scanning sites. Each one is a quick win.
Watch out for:
Frequently Asked Questions
The HTTP Header Checker is a free tool that helps you analyze and debug various aspects of your website.
Yes, this tool is completely free with no signup required.
Simply enter your URL and our tool will analyze it and show you the results.
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Secure By Default
HSTS, HTTPS, and modern TLS enforced everywhere
Edge Performance
Sub-50ms redirects with Brotli compression
Branded Domains
Use your domain with automatic SSL provisioning
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