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JWT Claim Signer & Local Auth Simulator

Security

Sign JWTs with custom claims (HS256/384/512, RS256, ES256), verify offline with Web Crypto, and simulate role-based API access. Pairs with JWT Debugger.

100% client-side

Web Crypto API · local auth simulator

Sign JWTs with custom claims, verify signatures offline, and simulate role-based API access — pairs with JWT Debugger. Secrets never leave your browser.

Algorithm

Header

Payload (claims)

HMAC secret

Public key (SPKI PEM)