Free tool · HTTP
Inspect HTTP response headers for diagnostic information. Enter an address to see the headers the server sends back with its answer.
Headers are short notes the server sends before the page itself: content type, caching rules, cookies and security settings.
Cache-Control and related headers decide how long browsers and CDNs keep a copy. Wrong values show up as stale pages or needless load on the server.
Headers such as Strict-Transport-Security and Content-Security-Policy protect visitors. A missing one is not an error, but it is worth knowing about.
Hosting providers, CDNs and proxies add their own headers on the way. They are part of the answer visitors receive.
No. The request is anonymous, like a visitor who is not signed in, so it sees what any visitor sees.
Yes, a limited number of them, and the headers shown are those of the final answer.
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