JWT Decoder
Decode the header and payload of a JWT without verification. Runs locally — tokens never leave your browser.
JWT token
Header
Payload
What this JWT decoder does
Decode the header and payload of a JSON Web Token (JWT) and read them as formatted JSON. The token is decoded in your browser and never transmitted. This tool only decodes — it does not verify the signature.
Anatomy of a JWT
Three parts. A JWT has the form
header.payload.signature, each part Base64URL-encoded. This tool decodes the first two.Header describes the signing algorithm, commonly
alg: HS256 or RS256.Payload holds claims such as
sub, exp (expiry), iat (issued at), andaud (audience). Expiry is a Unix timestamp in seconds.Signature is not decoded here. Never trust the payload of a JWT without verifying the signature on the server that issued it.