HTTP headers checker

Enter a URL to see the server's HTTP response: the status code, every header and, if there are redirects, each hop until the final page. Useful for checking 301 redirects, caching, compression or security headers.

What are HTTP headers?

Every time the browser requests a page, the server responds with a status code and a set of headers before the content. Headers state the content type (Content-Type), how long it may be cached (Cache-Control), whether it is compressed (Content-Encoding), cookies (Set-Cookie) or where to redirect (Location).

Status codes

2xx success (200 OK). 3xx redirection: 301 and 308 are permanent (search engines move rankings to the new URL), 302 and 307 are temporary and 304 means the content has not changed. 4xx client error: 403 forbidden, 404 not found, 410 gone, 429 too many requests. 5xx server error: 500 internal error, 502 and 504 proxy or gateway failures, 503 service unavailable.

For SEO, each old URL should redirect with a 301 straight to the final one, without multi-hop chains.

Security headers

Strict-Transport-Security (HSTS) forces the browser to always use HTTPS. Content-Security-Policy restricts where scripts and other resources can be loaded from, the best defence against XSS. X-Content-Type-Options: nosniff stops the browser from guessing a file's type. X-Frame-Options prevents the site from being embedded in another one (clickjacking). Referrer-Policy and Permissions-Policy control what information is sent to other sites and which browser APIs the page may use.