Website & SEO · HTTP

Website Header Checker

Every response carries a set of headers that decide how it is cached, compressed, secured and shared. Enter a URL to see all of them, on every redirect hop, with a plain-English note on what each one does.

Try

What each group tells you

Caching

Cache-Control, ETag, Age and Vary decide whether a browser or CDN may reuse the response, and for how long. Most "my change isn't showing" problems start here.

Compression

Content-Encoding: br or gzip means text is compressed on the wire. HTML, CSS and JavaScript sent without it are usually 3–5× larger than they need to be.

Security

Strict-Transport-Security, Content-Security-Policy and friends tell the browser how strictly to treat the page. The Security Headers Checker grades them in depth.

Server & CDN

Server, Via, CF-Cache-Status and X-Cache reveal what software and which CDN answered — and whether it came from the edge cache.

Cookies

Each Set-Cookie is listed separately with its flags. Session cookies without Secure and HttpOnly are flagged.

Redirects

Every hop is fetched separately and shown with its own headers, so a missing HSTS header or a 302 that should be a 301 in the middle of the chain is not hidden by the final page.

Questions

Why do I see different headers than my browser's dev tools?

Your browser sends cookies, a cached ETag and its own user agent, and may be served by a different CDN node. This check comes from our server with no cookies and no cache, which is how a first-time visitor or a crawler sees the page. Switch As to Mobile or Bot to see if the site varies by user agent.

GET or HEAD?

HEAD asks for headers only and is cheaper, but some servers answer it differently or reject it. GET is what a browser sends. If a server rejects HEAD, the check automatically retries with GET and says so.

Is the page body downloaded?

No. The request stops as soon as the headers arrive, so checking a large file is as fast as checking a small page.

Can I check internal or localhost addresses?

No. Private, loopback and cloud-metadata addresses are refused, including when a public URL redirects to one.

What else can you check?

These tools all work on the same connection and address data — pick whichever question you actually have.

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