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Performance
HTTP header inspector
HTTP header inspector
Full response headers, redirect chain, and request timing for any URL.
URL
Fetch
Copy share link
The link encodes your inputs in the URL fragment. Nothing is uploaded.
More tools
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Security headers
CSP, HSTS, X-Frame, Referrer-Policy, Permissions-Policy, COOP, CORP: graded A+ to F.
CORS tester
Send a preflight + actual request from a given Origin and see exactly which CORS headers the server returns.
Mixed content scanner
Scan an HTTPS page for HTTP src / href / action resources that modern browsers block.
JWT decoder
Header, payload, signature. Decoded entirely in your browser.
HMAC generator
HMAC-SHA1/256/384/512 with your key. Runs in your browser via Web Crypto.
JWT signature verify
Verify a JWT against a public key (PEM or JWK): entirely in your browser.