An Introduction to HTTP Security Headers

When your browser loads a website, the server doesn't just send the visible content; it also sends a set of invisible instructions called HTTP Headers. Many of these headers are crucial for telling your browser how to behave securely.

Think of them as a set of security rules that your website gives to every visitor's browser. Our tool performs a deep analysis of these headers to ensure your site is correctly configured to protect its users.

1. What are Protective Headers?

These are the most important headers for preventing common web attacks.

• Content-Security-Policy (CSP): This is the single most powerful security header. It defines a whitelist of approved sources from which your site is allowed to load content (like scripts, styles, and images). A strong CSP is the best defense against Cross-Site Scripting (XSS) attacks, where an attacker tries to inject malicious code into your pages. Our tool checks if your CSP is too permissive (e.g., contains 'unsafe-inline').
• Strict-Transport-Security (HSTS): This header tells browsers to only ever communicate with your site over a secure https:// connection. It's a critical defense against downgrade attacks and ensures all traffic is encrypted. We check if your HSTS policy has a long max-age and includes subdomains.

2. What are Cross-Origin & Isolation Policies?

This is a modern suite of headers designed to protect against advanced browser-level attacks and prevent your site from being abused by others.

• X-Frame-Options: A simple but effective header that prevents other websites from embedding your site in an iframe. This is the primary defense against clickjacking, where an attacker places an invisible frame over your site to trick users into clicking things they can't see.
• Cross-Origin Policies (COOP, COEP, CORP): This advanced set of headers provides deeper browser isolation, protecting against data leaks from sophisticated attacks like Spectre.

3. What is Cookie Security?

Cookies are small pieces of data used to manage user sessions. If they are stolen, an attacker can hijack a user's account. Our tool checks every cookie your site sets to ensure it has the proper security flags: * HttpOnly: Prevents the cookie from being accessed by JavaScript, mitigating XSS attacks. * Secure: Ensures the cookie is only ever sent over a secure https:// connection. * SameSite: A powerful defense against Cross-Site Request Forgery (CSRF) attacks.

By correctly implementing these headers, you turn every user's browser into an active partner in defending your website and their data.