HTTP Header Checker
This free HTTP header checker shows every response header a website sends, after following its redirects, and explains the common ones in plain English.
What are HTTP headers?
Headers are short notes a web server sends before the page itself. They tell the browser what kind of file it is, how long it may be cached, whether it was compressed, and which security rules apply.
You don't see them on the page, but they decide a lot about speed, caching and safety. Checking them is often the quickest way to find out why a change isn't showing or a page isn't cached.
The headers worth checking first
Cache-Control, Age and the CDN's cache header (like cf-cache-status) tell you whether pages are served from cache. Content-Encoding shows whether compression is on.
Strict-Transport-Security, Content-Security-Policy and X-Content-Type-Options are security headers. Our security headers checker grades those and shows how to add the missing ones.
Frequently asked questions
Why don't you show cookie values?
Cookies can hold session IDs and other private data, so we only show that a cookie was set and its flags (Secure, HttpOnly, SameSite). Never its name or value.
Do you follow redirects?
Yes, up to 10 hops. We show the headers of the final page and list the redirect chain above them.
Why are the headers different from what my browser sees?
Servers and CDNs can answer differently depending on location, cookies, login state and the browser. We fetch as a plain visitor with no cookies.
Can you check a site on a custom port or an IP address?
No. For safety we only check public websites by domain name on the standard ports, 80 and 443.