HTTP headers lookup

What is an HTTP Headers Lookup?

Every time a browser requests a web page, the server answers with a set of HTTP response headers before sending the body. These headers carry the status code, the content type, caching rules, compression, security policies and often the server software in use. An HTTP header lookup sends a request to a URL and displays those headers exactly as the server returned them, which is essential for debugging performance, security and compatibility issues.

How to Use the HTTP Headers Tool

Enter a full URL (for example https://example.com/page) and press the Inspect button. The tool performs a request and shows you the HTTP status line, such as 200 OK or 301 Moved Permanently, followed by every response header the server sent. You can read the cache-control rules to understand how a resource is cached, check for security headers like Content-Security-Policy and Strict-Transport-Security, and confirm that encoding, content type and CORS headers are set as expected. Redirects are shown so you can trace the chain.

Common Use Cases

Developers verify that a CDN or cache directive is actually being applied by inspecting the cache-control and cf-cache-status headers. Security engineers audit that security headers such as HSTS, CSP and X-Frame-Options are present and correctly configured. SEO and performance teams confirm content-type and compression behave properly, and support engineers diagnose redirect loops and server misconfigurations by watching how a URL answers.

Limitations

The headers shown are those returned to the checker's client, which may differ from a regular browser if the server varies its response by user agent or by the presence of cookies. Dynamic pages and authenticated endpoints that require a session will return their public, unauthenticated response. And because this sends standard requests, resources that block non-browser clients may return a challenge instead of the expected content.