HTTP Security Headers Checker

Inspect HTTP response headers for OWASP recommended security protections: HSTS, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and server fingerprint leaks.

HTTP Security Headers & OWASP Defense Standards

HTTP security headers instruct web browsers how to handle content, restrict framing, prevent cross-site scripting (XSS), and enforce encrypted transport protocols. Hardening web servers with modern security headers prevents client-side vulnerabilities without modifying underlying web application code.

Core Security Headers Breakdown

1. HTTP Strict Transport Security (HSTS)

Defined under RFC 6797, HSTS forces browsers to communicate exclusively over encrypted HTTPS connections, mitigating SSL-stripping and man-in-the-middle (MITM) attacks:

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

2. Content Security Policy (CSP)

Defined under W3C CSP Level 3, CSP restricts the domains and resource types (scripts, images, stylesheets, fonts) that a browser is permitted to execute, acting as the primary defense against Cross-Site Scripting (XSS) and data exfiltration.

3. X-Frame-Options & Clickjacking Defense

Defined under RFC 7034, X-Frame-Options: DENY or SAMEORIGIN prevents malicious third-party websites from rendering your web pages inside hidden <iframe> overlays to hijack user clicks.

4. X-Content-Type-Options

Setting X-Content-Type-Options: nosniff forces the browser to adhere strictly to the MIME type sent in the Content-Type header, preventing MIME confusion attacks where user-uploaded images are executed as JavaScript.

Server Implementation Snippets

Nginx Web Server Configuration

# Nginx Security Headers Configuration
add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
add_header X-Frame-Options "SAMEORIGIN" always;
add_header X-Content-Type-Options "nosniff" always;
add_header Referrer-Policy "strict-origin-when-cross-origin" always;
add_header Permissions-Policy "camera=(), microphone=(), geolocation=()" always;
add_header Content-Security-Policy "default-src 'self'; script-src 'self' https:; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:;" always;

Apache Web Server (.htaccess)

# Apache .htaccess Security Headers
<IfModule mod_headers.c>
  Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"
  Header always set X-Frame-Options "SAMEORIGIN"
  Header always set X-Content-Type-Options "nosniff"
  Header always set Referrer-Policy "strict-origin-when-cross-origin"
  Header always set Permissions-Policy "camera=(), microphone=(), geolocation=()"
</IfModule>

Security & Technical SEO Synergy

Security posture directly correlates with search engine trust and brand integrity:

  • Certificate Chain Validation: Validate your TLS handshake parameters and cipher strength with our SSL Certificate Checker.
  • Email Domain Protection: Prevent email phishing and spoofing with our DMARC & SPF Validator.
  • Redirect Chain Hygiene: Ensure HTTPS downgrade hops do not expose user credentials using our Redirect Chain Checker.

Frequently Asked Questions

What is HSTS Preloading?

HSTS Preload is a global directory baked into major browsers (Chrome, Firefox, Safari) where domains are hardcoded to load strictly over HTTPS, protecting the very first connection before the server can return an HSTS header.

Why is "unsafe-inline" in CSP dangerous?

The 'unsafe-inline' directive permits execution of inline <script> tags and DOM event handlers (e.g. onclick), neutralizing primary XSS defenses.

Does missing security headers affect Google search rankings?

While HTTPS is a direct ranking signal, missing secondary headers like CSP does not directly lower rankings. However, failing headers leave sites vulnerable to defacement, injection, and blacklisting which permanently damage organic search visibility.