Free HTTP Header Checker
Inspect every HTTP response header returned by any URL — including each redirect hop. Includes a security audit for key headers like CSP, HSTS, and X-Frame-Options — no signup required.
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Enter a URL above to inspect its HTTP response headers and security configuration.
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Why HTTP Headers Matter
HTTP headers are invisible to most users but critical for performance, security, and SEO. Missing security headers leave your site open to XSS, clickjacking, and protocol downgrade attacks. Wrong caching headers cause stale content or unnecessary server load.
Security Posture
Security headers like CSP and HSTS are a first line of defence against injection attacks, clickjacking, and insecure connections. This tool audits four critical security headers instantly.
SEO & Performance
Cache-Control, Content-Encoding, and server timing headers directly affect page speed — a Google ranking factor. Inspecting them helps diagnose slow TTFB.
- Missing HSTS lets attackers downgrade HTTPS connections to HTTP
- No X-Frame-Options allows your pages to be embedded in malicious iframes
- No X-Content-Type-Options enables MIME confusion attacks in older browsers
How It Works
Three steps from URL to a full header and security analysis.
Enter URL
Paste any URL — we fetch it server-side (following redirects) so you see what the final response sends.
Header Extraction
All response headers are captured, sorted alphabetically, and displayed in a searchable table.
Security Audit
Four critical security headers are checked for presence, with pass/fail badges and a short explanation of each.
Who Uses This Tool
Developers, security engineers, and SEO specialists who care about what servers actually send.
Web Developers
Verify caching, compression, and CORS headers are set correctly after deployments.
Security Teams
Audit security headers as part of penetration testing and compliance reviews.
SEO Specialists
Check X-Robots-Tag, canonical hints, and server timing headers affecting crawl.
DevOps Engineers
Debug CDN and load balancer header injection issues without needing curl access.
Frequently Asked Questions
What are HTTP response headers?
HTTP response headers are key-value pairs sent by a server alongside a web page. They control caching, security policies, content types, redirects, and more. Browsers and search engine crawlers read them to decide how to handle the response.
Which security headers should every site have?
At minimum: Strict-Transport-Security (enforce HTTPS), X-Frame-Options (prevent clickjacking), X-Content-Type-Options (prevent MIME sniffing), and Content-Security-Policy (restrict resources). This tool checks whether all four are present (it does not validate their values).
What is Content-Security-Policy (CSP)?
CSP is a powerful security header that tells browsers which sources of scripts, styles, images, and other resources are allowed. It is one of the most effective defences against cross-site scripting (XSS) attacks.
What is HSTS (Strict-Transport-Security)?
HSTS tells browsers to always connect to your site over HTTPS — even if a user types "http://". This prevents protocol downgrade attacks and cookie hijacking on insecure networks.
Does this tool affect my server or headers?
No. This tool only performs a read-only GET request to your URL from our server, following redirects, and reports the headers of the final response. Nothing is written to your server or configuration.
Go Beyond Headers —
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Key terms explained
Plain-English definitions from the LazySEO SEO glossary.