JWT Decoder & Inspector
Paste a JSON Web Token to decode its header, payload, and check expiration — all locally.
Header (JOSE)
Payload (Claims)
Signature
This tool only decodes the JWT. It does not verify the signature — server-side validation is required for security.
What is a JWT?
A JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. JWTs have three parts separated by dots: a Header (algorithm & type), a Payload (claims/data), and a Signature (integrity verification). They're widely used in OAuth 2.0 / OpenID Connect for authentication and API authorization.
Common Claims
sub (subject), iss (issuer), exp (expiration), iat (issued at), aud (audience), and nbf (not before). Custom claims can hold any application-specific data.