JWT Signature Verification

Verify JSON Web Token signature validity. Supports HS256/384/512, RS256/384/512, ES256/384, EdDSA.

JWT Token

AlgorithmAuto-detected from token header; can be overridden manually

Verification Options

Check expiration (exp)

Check not-before (nbf)

Check audience (aud)

JWT (JSON Web Token) is an open standard (RFC 7519) for securely transmitting claims between two parties.

HS256/384/512: HMAC symmetric signing; verifier must hold the same key
RS256/384/512: RSA asymmetric signing; verifier only needs the public key
ES256/384: ECDSA elliptic curve signing; smaller public key, high performance
EdDSA: Ed25519 modern signing algorithm
The algorithm is auto-detected from the token header and can be overridden manually

Note: This tool verifies tokens entirely in the browser; no token is sent to any server.