deftools.io Domain & Network

HTTP Headers Checker

View HTTP response headers for any URL. Inspect security headers, copy all headers, copy as curl command.

About this tool

Every HTTP response carries a set of headers — metadata such as Content-Type, Cache-Control, Strict-Transport-Security, Server, and X-Frame-Options — that tell the browser and any intermediary how to handle the body. This tool fetches a URL and lists every header the server actually returned, alongside the status code and elapsed time.

It is the quickest way to verify that a redirect is in place, confirm a security header such as Content-Security-Policy is being sent, or debug why a browser is caching stale assets. Enter https://example.com and the report shows 200 OK, the server (ECS), age, and cache miss/hit indicators.

Requests are routed through a CORS proxy because browsers block cross-origin header reads; the headers shown are exactly what the origin server sent to that proxy.

FAQ

Why do I see different headers than curl shows?

The request goes through a proxy, so some CDNs add headers like X-Cache or Via that reflect the proxy hop. Origin-only headers (those guarded by Access-Control-Expose-Headers) may also be hidden from the browser.

Can it follow redirects?

The tool reports the final response after redirects. Each hop adds its own headers, but only the last one is displayed — check the status code to spot a 301/302 that resolved to a 200.

Does it send cookies or auth?

No. The request is anonymous and unauthenticated, which is why protected endpoints may return 401 or 403. Use it to inspect public-facing behaviour, not authenticated flows.

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