← All checks

security · security.strict-transport-security.missing

Missing HSTS header

HSTS forces browsers to upgrade HTTP requests to HTTPS automatically, preventing downgrade attacks.

Why it matters

Without HSTS, a man-in-the-middle attacker can strip TLS from the very first request.

Example fix

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

Authoritative reference

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security

Run a full audit of your site

Free, no signup, no crawl cap. Check this and 40+ other factors across every public page.

Audit my site →

Related checks in security