babl.one Plugin :: @babl.one/client-jwt

The ClientJWT utility is a lightweight decoder used on the client side to extract payload data from a JSON Web Token (JWT). It does not verify signatures and is intended only for decoding JWTs where validation is handled on the server.

Overview

The ClientJWT Plugin allows for simple parsing of JWT tokens in the browser. It does not require a secret key and is primarily used to extract payload data for client-side use such as rendering UI or checking local user state.

Features

• Decode JWT payloads without verifying signatures.
• Gracefully handle malformed or expired tokens.
• Designed for browser environments.
• Returns token status alongside the payload.

Installation

You can include the ClientJWT utility directly in your browser-based application.

If bundled in your project:

npm install @babl.one/client-jwt

Or manually include the file if not using a package manager.

Usage

Import and Parse JWT

import ClientJWT from '@babl.one/client-jwt';

const token = localStorage.getItem("authJWT") || "";
const parsed = ClientJWT.parse(token);

if (parsed.status === "INSECURE") {
    console.log("User ID:", parsed.payload.userId);
}

API

static parse(jwt: string): { status: JWTStatuses, payload: any }

Parses the JWT token and returns the decoded payload and a status.

Parameters

• jwt: The encoded JWT string.

Returns

• status: "INSECURE" if decoding was successful but not verified.
• status: "INVALID" if the JWT is malformed or cannot be parsed.
• payload: Decoded payload object, or an empty object on failure.

Token Statuses

• INSECURE: Token was parsed successfully, but not verified.
• INVALID: Token format was incorrect or decoding failed.

Example

const result = ClientJWT.parse(token);
if (result.status === "INSECURE") {
    console.log(result.payload);
} else {
    console.warn("Invalid token");
}

Security Notice

This client-side JWT decoder does not verify the signature. Use it only for non-sensitive scenarios where the JWT has already been validated on the server.

If you need cryptographic integrity, use the server-side JWT plugin with blake2b512 validation.

Generated by the babl.one framework.