Question 1

What HTTP headers can I check?

Accepted Answer

You can check all standard HTTP response headers including status code, Content-Type, Cache-Control, CORS headers (Access-Control-Allow-Origin), Set-Cookie, Server, and any custom headers returned by the server. Headers available depend on what the server sends back and CORS policy.

Question 2

Does this tool send my request through an external server?

Accepted Answer

No. The header check runs entirely in your browser using the Fetch API. Your request goes directly from your browser to the target URL. However, due to browser CORS restrictions, some URLs may not return all headers. For full header inspection of any URL, use your browser's DevTools Network tab.

Question 3

Why do I only see some headers?

Accepted Answer

Browser security (CORS) limits which headers are accessible via JavaScript fetch(). For same-origin requests or servers that include a permissive Access-Control-Expose-Headers response header, you will see the full set. For other servers, only basic headers like Content-Type may be visible.

📋 HTTP Header Checker

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