HTTP Status Code Checker

What this checker can report

The browser does not reveal every redirect hop through a normal cross-origin Fetch request. You cannot use this result as a redirect-chain trace: intermediate status codes, Location values and timings are unavailable. A dedicated server-side redirect checker can inspect public targets hop by hop, with separate safeguards against private-network access.

Browser, CORS and privacy boundaries

The request goes from this browser directly to the target. Hyperion does not receive the URL or make the network request. Cookies, HTTP authentication credentials and the page referrer are omitted. The target still receives your IP address, the requested URL, the HEAD or GET method and normal browser request headers. In funnel mode, the URL and method are held briefly in this tab’s session storage between steps and disappear when that tab session ends or you start over.

Cross-origin status checks work only when the target’s CORS policy allows this origin to read the response. no-cors is not a workaround: it produces an opaque response whose status is exposed to JavaScript as 0. A CORS, DNS, TLS, mixed-content, private-network or connection failure can therefore look the same in this interface. Such an error does not prove that the site is down.

The checker accepts only HTTP and HTTPS URLs without embedded credentials. It rejects localhost and literal private or link-local addresses. Since browser JavaScript cannot reliably resolve and verify every hostname before Fetch, the browser’s own CORS and private-network protections remain part of the boundary.

HEAD, GET and redirects

RFC 9110 defines HEAD as identical to GET except that the server must not send response content. Some applications implement HEAD incorrectly or disable it, so compare with GET when the result is unexpected. In GET mode this checker cancels the response stream after headers become available; some body bytes may already have crossed the network, and no body preview is shown.

The final status is not necessarily the status of the URL you entered. Fetch follows redirects automatically. Codes 301 and 308 indicate permanent moves, while 302 and 307 indicate temporary moves. Codes 307 and 308 preserve the request method; 301 and 302 allow user agents to change POST to GET, although this checker sends only HEAD or GET.

Reading common status classes

A 304 response belongs to a conditional request and means a stored representation can be reused; it is not a general success code to expect from an ordinary check. A 401 response requests authentication, while 403 means the server understood the request but refuses to fulfil it. The English reason names in the reference are conventional protocol labels; the numeric status is authoritative.