WebAuthn / Passkey Debugger
NewDecode WebAuthn clientDataJSON, authenticatorData and attestationObject, inspect flags and credential public keys, or create a test passkey to see real values.
webauthn debuggerpasskey debuggerauthenticatorData decoderclientDataJSONcbor decoder
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The live test runs entirely locally (rp.id = this site's hostname) and nothing is sent anywhere.
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Frequently Asked Questions
What can I decode?
clientDataJSON, authenticatorData (RP ID hash, flags, counter, credential data) and attestationObject (CBOR).
Can I generate sample data?
Yes, the tool can create a temporary passkey with your browser and show the resulting values. Nothing is sent anywhere.
What do the flags mean?
UP is user presence, UV is user verification, BE/BS indicate backup eligibility and state, AT means attested credential data is included.
Does it verify signatures?
No, it is a decoder for debugging; signature verification belongs on your server.