JWT Decoder

Structure of a JWT

A JWT has three parts separated by dots: header.payload.signature. The header and payload are JSON objects encoded with Base64URL without padding. The signature is computed over the first two parts with the algorithm named in the header (alg), for example HS256 or RS256.

Registered claims

Decode a JWT in JavaScript

const [h, p] = token.split('.');
const json = (s) => JSON.parse(new TextDecoder().decode(
  Uint8Array.from(atob(s.replace(/-/g, '+').replace(/_/g, '/')), (c) => c.charCodeAt(0))));
console.log(json(h), json(p));