HTTP Security Headers Checker

Check HTTP security headers for any website free online. See if HSTS, CSP, X-Frame-Options, and other protective headers are present, with explanations for each.

How to Use This Tool

Enter the website URLAdd the full URL including https://

Click Check HeadersResponse headers are fetched and analyzed

Review each security headerSee which protections are present or missing

Security Headers Are Cheap Insurance Against Well-Known Attacks

Most web application attacks fall into a small number of well-documented categories -- cross-site scripting, clickjacking, protocol downgrade attacks. HTTP security headers exist specifically to close these off, and unlike fixing application logic bugs, adding them is usually a configuration change rather than a code change, making missing headers one of the most cost-effective gaps to close.

This checker fetches a site's actual HTTP response and evaluates whether the major protective headers are present, explaining what each one defends against so you understand the real-world impact of a gap, not just a pass/fail checkmark.

The Headers That Matter Most

Strict-Transport-Security prevents protocol downgrade attacks. Content-Security-Policy is the primary defense against cross-site scripting by restricting what scripts can execute and where they can communicate. X-Content-Type-Options prevents MIME-type sniffing attacks. X-Frame-Options or frame-ancestors in CSP prevents clickjacking by controlling iframe embedding. Each addresses a distinct, well-understood attack category.

Configuration, Not Code Rewriting

Adding these headers typically happens at the web server, reverse proxy, or CDN level -- an Nginx or Apache config change, an IIS web.config update, or a Cloudflare rule -- rather than requiring changes inside the application itself. This is part of why missing security headers are often genuinely an oversight rather than a deliberate tradeoff: they are easy to add once someone checks for them.

Frequently Asked Questions

HTTP Strict Transport Security tells browsers to only ever connect via HTTPS, never plain HTTP, for a specified duration. Without it, a user's first connection attempt could potentially be intercepted and downgraded to unencrypted HTTP by an attacker in a man-in-the-middle position before the browser even knows to require HTTPS.

CSP restricts which sources scripts, styles, and other resources can load from, which is one of the most effective defenses against cross-site scripting (XSS) attacks. Without it, if an attacker manages to inject malicious script into a page, the browser will execute it with no restriction. With a strict CSP, even injected scripts often cannot run or communicate with attacker-controlled domains.

These headers control whether your site can be embedded in an iframe on another site. Without this protection, a malicious site could overlay your page in an invisible iframe and trick users into clicking buttons they think belong to a different site -- an attack called clickjacking.

Not automatically a confirmed breach, but each missing header removes a layer of defense that costs nothing to add and provides real protection against well-documented attack categories. Security works in layers, and these headers are some of the cheapest layers to add.

In most cases yes -- security headers are typically configured at the web server or reverse proxy level (Nginx, Apache, IIS, or a CDN like Cloudflare), which means they can usually be added through configuration rather than requiring changes to your application's source code.