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Security Headers Checker

Check a website's HTTP security headers — HSTS, CSP, X-Frame-Options, Referrer-Policy and more — get a grade and how to fix each gap.

HTTP security headers are instructions a website sends to the browser: always use HTTPS, only run scripts from these places, don't let other sites frame this page, don't guess file types, don't leak full addresses to other sites, and keep the camera and microphone off. They cost nothing to add and block whole classes of attacks, yet many sites miss several of them.

Enter a website address and this checker fetches its response headers, follows any redirects, and grades the site from A+ to F. Each check says what was found and, where something is missing or weak, the exact header to add. It also points out cookies without the Secure, HttpOnly or SameSite flags and headers that reveal software versions. Only the headers are read — never the page content — and the address you check is not stored.

How to use Security Headers Checker

  1. Enter the website address, such as example.com.
  2. Press Check headers.
  3. Read the grade and each finding.
  4. Add the suggested headers in your server or CDN, then check again.

Features

  • Strict-Transport-Security, including max-age.
  • Content-Security-Policy strength.
  • Clickjacking protection (X-Frame-Options or frame-ancestors).
  • X-Content-Type-Options, Referrer-Policy, Permissions-Policy, Cross-Origin-Opener-Policy.
  • Cookie flags and version leaks.
  • Grade from A+ to F with fixes for each gap.
  • All response headers shown.

What is checked and how it is scored

The grade is based on points for each header. Sites that don't end up on HTTPS always score F, because the other protections can be stripped in transit.

HeaderPointsGood value
Strict-Transport-Security25max-age of at least 180 days
Content-Security-Policy25A policy that restricts scripts
X-Frame-Options or frame-ancestors15DENY / SAMEORIGIN or 'none' / 'self'
X-Content-Type-Options10nosniff
Referrer-Policy10strict-origin-when-cross-origin or stricter
Permissions-Policy10Present
Cross-Origin-Opener-Policy5same-origin

Reading the results

Green findings are fine. Amber findings work but could be stronger — for example a short HSTS max-age, or a CSP that still allows inline scripts. Red findings are missing protections that are easy to add. Grey notes are informational: software versions in Server or X-Powered-By headers help attackers find known vulnerabilities, and cookies without Secure, HttpOnly and SameSite can be stolen or sent in cross-site requests.

Adding the headers

Headers are set where your site is served: in the web server (nginx add_header, Apache Header set), in a CDN such as Cloudflare (Transform Rules), in your hosting dashboard, or in your application framework. Add one at a time and check the site still works — especially the Content-Security-Policy, which is best introduced in report-only mode. The CSP Generator and Permissions-Policy Generator build those two for you.

How the check works

Browsers are not allowed to read another website's headers directly, so the address is fetched by this site's small checking service on Cloudflare's network. It requests the page once, follows up to five redirects, reads only the response headers and returns them; the page itself is never downloaded or stored. Private, local and internal addresses are refused, and each visitor can run about 30 checks a minute. The result reflects what the server sends to a normal browser request at that moment.

Limits

Headers can differ between pages, so check the important ones — the home page, the login page and an account page. Some protections, such as HSTS preloading, can't be seen in a single response. A good grade is a strong start, not a full security review: keep software updated and test your application itself as well.

Frequently asked questions

Can I see every header the site sends?

Yes. Open All response headers under the results.

Do redirects affect the result?

Redirects are followed, up to five, and the final page's headers are graded.

Will adding headers slow my site down?

No. Headers add a few hundred bytes and no extra requests.

How do I check my website's security headers?

Enter the address and press Check headers.

What is a good grade?

A or A+. Most sites can reach A by adding a few headers.

Which security headers should every site have?

Strict-Transport-Security, Content-Security-Policy, X-Frame-Options or frame-ancestors, X-Content-Type-Options and Referrer-Policy.

Why is my site graded F?

It doesn't end up on HTTPS, or most key headers are missing.

Is the page content downloaded?

No. Only the response headers are read.

Can I check internal or local sites?

No. Private and local addresses are refused.

How often can I check?

Up to 30 checks a minute.

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