Security Headers Checker
Use this free security headers checker to instantly analyze the HTTP response headers returned by any website. Identify missing protections, detect information disclosure, and generate copy-paste configuration fixes for your server.
What is HTTP Security Headers?
HTTP security headers are directives that web servers include in HTTP responses to instruct browsers on how to behave when handling your site's content. These headers form a critical layer of defense against common web attacks including cross-site scripting (XSS), clickjacking, protocol downgrade attacks, and information disclosure. Unlike firewall rules or application-level controls, security headers are lightweight — a single line of configuration can prevent entire categories of attacks.
Why It Matters
Missing or misconfigured security headers are one of the most common findings in professional web application penetration tests. They are consistently listed in the OWASP Top 10 under "Security Misconfiguration." Despite being easy to implement, many production websites — including those of large enterprises — fail basic security header checks. For businesses, missing headers can mean GDPR non-compliance, PCI-DSS audit failures, and real user data exposure to attackers.
Common Configuration Mistakes
- ✗Configuring security headers in development but not in production
- ✗Setting headers on the homepage but not on API endpoints or subdomains
- ✗Using weak HSTS max-age values that expire within days
- ✗Implementing CSP with broad wildcards or unsafe-inline that negate its protection
- ✗Leaving X-Powered-By and Server headers that expose technology details
- ✗Not testing after CDN or proxy configuration (headers may be stripped)
- ✗Forgetting to apply headers to error pages (401, 403, 404, 500)
Recommended Configuration
# Recommended minimum security header set Strict-Transport-Security: max-age=31536000; includeSubDomains; preload Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; font-src 'self' data:; connect-src 'self'; frame-ancestors 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; upgrade-insecure-requests; X-Frame-Options: SAMEORIGIN X-Content-Type-Options: nosniff Referrer-Policy: strict-origin-when-cross-origin Permissions-Policy: camera=(), microphone=(), geolocation=(), payment=() Cross-Origin-Opener-Policy: same-origin Cross-Origin-Resource-Policy: same-origin
Frequently Asked Questions
What are HTTP security headers?
HTTP security headers are server response headers that instruct browsers on how to behave when processing your website's content. They defend against attacks like XSS, clickjacking, and MIME sniffing by controlling browser behavior at the protocol level.
Will adding security headers break my website?
Most headers are safe to add without breaking functionality. Content-Security-Policy is the exception — a strict CSP can break third-party scripts, analytics, and CDN-loaded resources. Always start with Content-Security-Policy-Report-Only to test your policy before enforcing it.
How do I check security headers without a tool?
Open Chrome DevTools → Network tab → reload the page → click the document request → Headers tab. You'll see all response headers. Alternatively, use curl: curl -I https://yourdomain.com
Do security headers affect SEO?
Security headers do not directly impact search rankings. However, HTTPS (enforced by HSTS) is a Google ranking factor. A well-secured site also builds user trust, indirectly improving conversion rates and engagement metrics that influence SEO.
How often should I re-check my security headers?
After every major infrastructure change, web server update, CDN configuration change, or new third-party integration. At minimum, scan quarterly as part of routine security hygiene.
Related Tools & Guides
Need Professional Web Application Security Testing?
This scanner checks visible headers. VAPT Experts provides professional web application penetration testing, API security testing, and compliance-ready security reports.
Request VAPT Assessment