JWT Decoder

Tool Overview

The JWT Decoder allows you to decode and inspect JSON Web Tokens (JWT). JWTs are commonly used for authentication and authorization in web applications. This tool helps you view the token's header, payload, and verify its structure.

How It Works

JWT (JSON Web Token) consists of three Base64-encoded parts separated by periods for secure transmission and authentication.

JWT Structure

Component Breakdown

1. Header: Base64-encoded JSON containing:
   • alg: Algorithm used for signing (e.g., HS256, RS256)
   • typ: Token type (typically "JWT")
2. Payload: Base64-encoded JSON containing claims:
   • iss: Issuer of the token
   • sub: Subject of the token
   • exp: Expiration time (Unix timestamp)
   • iat: Time the token was issued
   • aud: Audience the token is intended for
3. Signature: Digital signature computed using the header-specified algorithm.
4. Metadata: Auto-generated information derived from the payload:
   • token_status: Current status (Valid, Expired, or Not Yet Valid)
   • issued_at: Human-readable issued timestamp
   • expires_at: Human-readable expiration timestamp
   • time_remaining: Time remaining until expiration (e.g., "5d 3h 12m")

Decoding Process

1. Split: The token is split at each period into three parts.
2. Base64 Decode: Each part is decoded using Base64 URL-safe decoding.
3. JSON Parse: The decoded strings are parsed into JSON objects.
4. Display: The header and payload are displayed with syntax highlighting.

Important Notes

The tool also checks for common JWT structure issues and provides error messages for invalid tokens. Users should verify signatures using the appropriate public key in production environments.

Features

• Decode JWT header and payload
• Display decoded JSON with syntax highlighting
• Show token expiration status
• Display common claims (exp, iat, iss, sub, aud)
• Copy decoded content to clipboard

Usage Examples

Example 1: Decode Standard JWT

Input:

Output:

Example 2: Token with Expiration

Input:

Output:

FAQ