Is this tool safe to use?

Yes. The request is made from devformat.tools to the URL you provide. Your IP, browser, and any data outside the URL itself are never exposed to the target server. We block requests to private IPs and metadata endpoints (SSRF-safe).

Can I inspect headers for sites behind authentication?

Not yet. The tool sends an anonymous GET — sites that require cookies, OAuth, or API keys will return 401/403. Public endpoints work fine.

What headers are most useful to check?

Content-Security-Policy, Strict-Transport-Security, X-Frame-Options, Cache-Control, Set-Cookie, Cross-Origin-* headers, and the response status. The viewer outputs all of them sorted alphabetically.

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HTTP Header Viewer

Processed securely

Input

Output

Ready

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How to Use

Paste a public URL (HTTP or HTTPS) into the input.
Click Run. The server performs a GET and returns the response headers.
Inspect status, cache, security, and CORS headers in the output.

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Inspect HTTP Response Headers

Paste any public URL and get the full set of response headers â status code, content type, caching directives, CORS rules, security headers, and cookies â without firing up curl. Useful for debugging redirects, missing security headers, broken CORS, and CDN behaviour.

What This Tool Catches

Common findings: missing Strict-Transport-Security, weak or missing Content-Security-Policy, overly-permissive Access-Control-Allow-Origin, missing X-Content-Type-Options: nosniff, and Cache-Control mistakes that leak private content into shared caches.

Privacy

The fetch is performed from our server. Your IP and browser fingerprint never reach the target. We block requests to localhost, private networks, and cloud metadata endpoints to prevent SSRF abuse.