Check if your website has the right security settings. We'll explain what each one does in plain English.
Security headers are instructions your website sends to visitors' browsers. They tell the browser how to behave and what to allow, helping protect your visitors from various attacks.
Think of them as security rules that lock doors hackers might try to use. Without them, your website and visitors are more vulnerable to attacks.
Came from the securityheaders.com API? Snyk discontinued it in April 2026. We're a free drop-in with the same A+→F grades — see the one-line migration guide, or read the API docs.
HTTP security headers are response headers a web server sends to tell the browser how to behave — for example to force HTTPS, block your pages from being framed, or restrict which scripts can run. They add a layer of defence against attacks like cross-site scripting, clickjacking and protocol downgrade.
We check the core headers — Strict-Transport-Security (HSTS), Content-Security-Policy (CSP), X-Frame-Options, X-Content-Type-Options, Referrer-Policy and Permissions-Policy — plus HTTPS redirection, cookie flags, mixed content and the newer Cross-Origin isolation headers (COOP, COEP, CORP).
Grades run from A+ down to F. A+ or A means the important headers are present and well configured; B and C indicate missing or weak headers; F means little or no protection. Aim for at least an A, and add HSTS with a long max-age to reach A+.
A CSP that allows 'unsafe-inline' or 'unsafe-eval' in script-src weakens XSS protection, so the grade is capped at A even when every header is present. Removing those keywords and using nonces or hashes lets the page reach A+.
Security headers add negligible overhead and are not a direct ranking factor, but HTTPS with HSTS and a safer site improve user trust and reduce the risk of malware warnings that can hurt rankings.
The on-demand check is free and needs no account. Create a free account only if you want scheduled re-scans, history and alerts when a header regresses.
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