NETWORK TOOL

HTTP Header Checker

Inspect the HTTP response headers a website makes available to a browser.

HEADER CHECK

Enter a public HTTPS URL to inspect its response headers.

ABOUT THIS TOOL

What are HTTP headers?

HTTP headers carry information between a web browser and a server. They can describe content, caching behavior, security policies, cookies, and other aspects of an HTTP response.

This tool makes a browser request and displays the response headers that the browser allows client-side JavaScript to read. Some headers may be unavailable because of the target site's CORS policy.

Useful headers to look for

Security-related headers can include Content-Security-Policy, Strict-Transport-Security, X-Content-Type-Options, and Referrer-Policy.

FAQ

Common questions

Why can't I see every header?

Browsers restrict which cross-origin response headers JavaScript can read unless the destination explicitly permits access through CORS.

Does this tool change the website I check?

No. It sends a normal HTTP request and does not modify the target website.

Why do some sites fail the check?

A site may block cross-origin requests, require authentication, reject automated requests, or otherwise prevent browser-based inspection. A failure here does not necessarily mean the site is offline.