jwt-decoder-claims is a JS Library that allows to decode JWT (JSON Web Token), resolving the claims payload and header from the tokens.

This library doesn't serve to verify the signature of the token or to validate it, this only allows to decode the content of the token namely the payload and the header.

Installation

Install through NPM : npm install jwt-decoder-claims Install through Yarn : yarn add jwt-decoder-claims

Usage

import JWTDecoder from "jwt-decoder-claims";

const token = "eyJ0eXBlIjoiSldUIiwiYWxnIjoiSFM1MTIifQ.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6Imp3dC1kZWNvZGVyIiwiaXNzIjoic2xpbWFuaSIsImlhdCI6MTUxNjIzOTAyMn0.mCi4zZRP7d9NQD-ULjBL9vB1NvicJD_FnmuFa1zJSfY88yBEpkLX_VExyAXG9XvLxRmrdocHlfzEHB6TTC3HrQ";

/*** decode the payload ***/
const claims = JWTDecoder.payload(token);
console.info(claims);

// prints : 
// {
//   "sub": "1234567890",
//   "name": "jwt-decoder",
//   "iss": "slimani",
//   "iat": 1516239022
// }

/*** decode the header ***/
const header = JWTDecoder.header(token);
console.info(header);

// prints: 
// {
//   "type": "JWT",
//   "alg": "HS512"
// }

/*** get the decoded entire claims data : header + payload ***/
const decodedToken = JWTDecoder.resolve(token);
console.info(decodedToken);

// prints :
// {
//     "header" : {
//         "type": "JWT",
//         "alg": "HS512"
//     },
//     "payload" : {
//         {
//             "sub": "1234567890",
//             "name": "jwt-decoder",
//             "iss": "slimani",
//             "iat": 1516239022
//         }
//     }
// }

Important! In case of malformed token it will throw an exception of invalid token error. It is recommanded to combine the decoding function with a Promise object or add try/catch block

Usage with promise object

import JWTDecoder from "jwt-decoder-claims";

decodeJWT = (token) => new Promise((resolve, reject) => {
    try {
        const claims = JWTDecoder.payload(token);
        resolve(claims);
    } catch (err) {
        reject(err);
    }
});

//use .then() implicitly to return a promise
decodeJWT(token).then((decoded) => {
    console.info(decoded);

    // prints : 
    // {
    //     "sub": "1234567890",
    //     "name": "jwt-decoder",
    //     "iss": "slimani",
    //     "iat": 1516239022
    // }

}, (error) => {
    console.error("Invalid token error "+error);
})

For CommonJS usage

const JWTDecoder = require('jwt-decoder-claims');

Github repository

If you have any contribution request, feature or if you found a bug or any issue please report them to this github repository

Demo application

jwt-decoder-claims has been used to decode the JWTs in this simple tool checkout here Here is the github repository for any feature or contribution.

Author

Brahim Slimani