Free Security Headers Checker
Enter a URL to check if it has the recommended HTTP security headers that protect your visitors from clickjacking, MIME sniffing, and protocol downgrade attacks.
What this security headers checker checks
This free security headers checker fetches your page and reports whether the recommended HTTP security headers are set, including HSTS (Strict-Transport-Security), X-Content-Type-Options, and X-Frame-Options. These headers are simple to add and protect your visitors from common attacks such as clickjacking, MIME-type sniffing, and protocol downgrade.
Security headers pair naturally with HTTPS: confirm your certificate and mixed-content status with the HTTPS checker.
Why security headers matter
Headers are instructions your server sends the browser about how to treat your page safely. Without them, a browser falls back to permissive defaults that attackers can exploit: your page could be framed inside a malicious site to trick users into clicking, or a file could be interpreted as a different type than you intended.
They cost nothing in performance and are a one-time configuration, which makes them one of the best effort-to-payoff security improvements available, and a signal to security-conscious users and auditors that you take safety seriously.
How to add the key security headers
Set these at your server, CDN, or framework config so they apply to every response:
- Strict-Transport-Security: forces browsers to use HTTPS for your domain, closing the downgrade window.
- X-Content-Type-Options: nosniff: stops the browser guessing content types, which prevents a class of injection attacks.
- X-Frame-Options: DENY or SAMEORIGIN: stops other sites embedding your pages in an iframe, blocking clickjacking.
- Content-Security-Policy: the most powerful header, restricting where scripts and resources can load from. Start in report-only mode to avoid breaking your site.
Honest limits
This tool checks for the presence of the core recommended headers on the single page you enter; it does not grade the strength of a full Content-Security-Policy. For a complete security and SEO sweep across your site with AI fix instructions and a PDF report, run a full free audit.
Frequently asked questions
Is this security headers checker free?
Yes, free with no signup, up to 15 checks per hour.
What is HSTS?
Strict-Transport-Security tells browsers to only ever connect to your domain over HTTPS, closing the window where a downgrade attack could occur.
What does X-Frame-Options do?
It controls whether other sites can embed your pages in an iframe. Setting it to DENY or SAMEORIGIN blocks clickjacking.
Where do I set security headers?
At your web server, CDN, or framework config, so they apply to every response. It is a one-time change with no performance cost.
Do security headers affect SEO?
Not directly, but they protect users and signal a well-maintained site. Pair them with HTTPS, checked by the HTTPS checker.