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What does this tool do?
JWT Signer & Verifier: operation mode, algorithm, header (json), payload (json), compact jwt token, secret key (or rsa private key pem), rsa public key pem (for rs256 verification) → compact jwt token, cryptographic signature validity, decoded header json, decoded payload json, claims validation (exp, nbf, clock skew). Process locally in your browser. Inputs: Operation Mode, Algorithm, Header (JSON), Payload (JSON), Compact JWT Token, Secret Key (or RSA Private Key PEM), RSA Public Key PEM (for RS256 Verification). Outputs: Compact JWT Token, Cryptographic Signature Validity, Decoded Header JSON, Decoded Payload JSON, Claims Validation (exp, nbf, clock skew).
How to use it?
Provide the listed input and choose Sign / Verify JWT. Review the result, then copy or download where available. Clear removes inputs and results.
Browser-local processing. No uploads, content logging, persistence or remote resource loading. Generated markup is inert text; files are treated as untrusted data.
100% in-browser cryptographic processing using Web Crypto API. Private keys, passphrases, AES-GCM payloads, and certificate requests are calculated client-side and never sent to any server.