Website & server tools

HTTP header checker

See exactly what a server returns: status codes at every redirect, the response headers and missing security headers.

Try:

HTTP status codes

The status code summarises the server's answer: 2xx success, 3xx redirect, 4xx client error (such as 404 not found), 5xx server error.

  • 301 / 308 — permanent redirect; search engines transfer ranking to the new URL.
  • 302 / 307 — temporary redirect.
  • 403 — forbidden; sometimes a firewall blocking automated checks like this one.
  • 503 — the service is temporarily unavailable.

Security headers

Headers such as Strict-Transport-Security and Content-Security-Policy tell browsers to enforce HTTPS and restrict what a page may load. Missing headers aren't always a problem, but they're cheap protection worth adding. Check the certificate itself with the SSL checker.

Questions

Why do I see different headers in my browser?

Servers can vary responses by browser, cookies, location or compression support. This tool sends a plain request with a clearly identified user agent.