Free Security Headers Checker
Review the response headers that help browsers enforce transport security, framing protections, content restrictions, MIME sniffing controls, and referrer privacy.
Common use cases
- Audit a new website before launch for missing browser security headers.
- Confirm HSTS, CSP, X-Frame-Options, and related headers after a deploy.
- Collect quick evidence for hardening tickets and security reviews.
Frequently asked questions
Which security headers are checked?
The checker reports common headers including HSTS, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and related controls.
Does it make a GET request?
NerdTools tries a HEAD request first and falls back to GET when the server does not return enough information.