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Understanding HTTP Security Headers
HTTP security headers are response headers that web servers send to browsers to enable security features and prevent common web vulnerabilities. Properly configured headers can protect against XSS, clickjacking, MIME-type sniffing, and other attacks.
Essential Security Headers
| Header | Purpose | Priority |
|---|---|---|
| Content-Security-Policy | Prevents XSS and code injection | Critical |
| Strict-Transport-Security | Enforces HTTPS connections | Critical |
| X-Frame-Options | Prevents clickjacking | High |
| X-Content-Type-Options | Prevents MIME sniffing | High |
| Referrer-Policy | Controls referrer information | Medium |
Content Security Policy (CSP)
CSP is the most powerful security header, allowing you to control which resources can be loaded on your page. A well-configured CSP can prevent most XSS attacks by blocking inline scripts and limiting script sources.
Example CSP Header:
Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'HSTS Configuration
HSTS should be configured with a max-age of at least 31536000 (1 year) and include the includeSubDomains directive. For additional security, consider adding your domain to the HSTS preload list.
Recommended HSTS Header:
Strict-Transport-Security: max-age=31536000; includeSubDomains; preloadCross-Origin Headers (COOP, COEP, CORP)
The newer cross-origin headers enable cross-origin isolation, which is required for some browser features like SharedArrayBuffer. However, they can break third-party integrations, so test carefully before deploying.
COOP
Cross-Origin-Opener-Policy isolates your browsing context from cross-origin windows.
COEP
Cross-Origin-Embedder-Policy requires all resources to opt-in to being loaded.
CORP
Cross-Origin-Resource-Policy controls who can load your resources.
Frequently Asked Questions
Common questions about the Security Headers Analyzer
This tool analyzes 13 key security headers: Content-Security-Policy (CSP), Strict-Transport-Security (HSTS), X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, Cross-Origin-Opener-Policy (COOP), Cross-Origin-Embedder-Policy (COEP), Cross-Origin-Resource-Policy (CORP), Expect-CT, X-XSS-Protection, X-Permitted-Cross-Domain-Policies, and X-DNS-Prefetch-Control.
Content-Security-Policy is a security header that helps prevent cross-site scripting (XSS), clickjacking, and other code injection attacks by specifying which content sources are allowed to load. A well-configured CSP significantly reduces the attack surface of your web application.
HTTP Strict Transport Security (HSTS) tells browsers to only connect to your site using HTTPS, preventing man-in-the-middle attacks and protocol downgrade attacks. With HSTS, even if a user types http://, their browser will automatically use HTTPS.
The security score is a weighted average of individual header scores. Critical headers like CSP (25%) and HSTS (20%) have higher weight, while informational headers like Expect-CT have lower weight. Each header is scored based on its presence and configuration quality.
Grades reflect your overall security posture: A+ (95+) means exceptional security, A (85-94) is excellent, B (75-84) is good but needs improvement, C (65-74) is moderate with several issues, D (50-64) is weak, and F (below 50) indicates critical security problems.
Yes! You can switch to "Paste Headers" mode and enter raw HTTP headers directly. This is useful for testing headers from development environments, analyzing headers from curl output, or checking headers when the site is not publicly accessible.
Security headers are typically configured in your web server (Nginx, Apache), CDN (Cloudflare, AWS CloudFront), or application framework. The tool provides specific recommendations and example configurations for each missing or weak header.
Yes, the tool automatically detects if a site is using Cloudflare based on response headers. When Cloudflare is detected, you will see specific guidance on how to configure security headers through the Cloudflare dashboard using Transform Rules.
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ℹ️ Disclaimer
This tool is provided for informational and educational purposes only. All processing happens entirely in your browser - no data is sent to or stored on our servers. While we strive for accuracy, we make no warranties about the completeness or reliability of results. Use at your own discretion.