JWT Tool

Professional JWT Token generator, decoder and validator with real-time processing. Create secure JSON Web Tokens for authentication and authorization with HS256, HS384, HS512 algorithms.

Configuration

Set JWT payload, secret key and algorithm

Generation Result

Generated JWT Token

Please configure payload and secret key to generate JWT Token

What is JWT (JSON Web Token)?

JWT (JSON Web Token) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. JWTs are digitally signed using a secret (HMAC algorithm) or a public/private key pair (RSA or ECDSA).

JWT Structure

A JWT consists of three parts separated by dots (.): Header.Payload.Signature

  • Header: Contains metadata about the token type and signing algorithm used
  • Payload: Contains the claims - statements about an entity (user) and additional data
  • Signature: Used to verify the token hasn't been tampered with and authenticate the issuer

Key Features

  • Compact: JWTs can be sent through URLs, POST parameters, or HTTP headers
  • Self-contained: Contains all necessary information about the user
  • Secure: Digitally signed to verify authenticity and prevent tampering
  • Stateless: No need to store session information on the server

Common JWT Use Cases

JWT tokens are widely used in modern web applications for various authentication and authorization scenarios

User Authentication

Verify user identity after login and maintain session state across requests without server-side storage

API Authorization

Secure REST APIs and microservices by including user permissions and roles in JWT claims

Single Sign-On (SSO)

Enable users to access multiple applications with one set of credentials across different domains

Information Exchange

Securely transmit information between parties with digital signatures ensuring data integrity

Mobile App Authentication

Authenticate mobile applications without cookies, perfect for stateless mobile backends

Microservices Communication

Pass user context and authorization data between microservices in distributed architectures

Why Use Our JWT Tool?

Multiple Algorithms Support

Generate and validate JWTs with HS256, HS384, and HS512 HMAC algorithms for different security levels

Real-time Generation & Decoding

Instantly create JWT tokens and decode existing ones with live preview and error detection

Security Best Practices

Follows JWT security standards with proper header validation and payload structure verification

Developer-Friendly Interface

Clean, intuitive interface designed for developers with syntax highlighting and clear error messages

No Server Dependencies

All JWT operations happen in your browser - no data sent to external servers for maximum security

Custom Payload Support

Create JWTs with custom claims, expiration times, and user-defined data structures

Token Validation

Decode and inspect JWT structure, claims, and expiration without needing the secret key

Copy & Export Ready

One-click copy functionality for immediate use in applications, APIs, and authentication systems

How to Use JWT Generator & Decoder

Complete guide to creating, validating and implementing JWT tokens in your applications

1

Step 1: Choose Operation Mode

Select 'Generate JWT' to create new tokens or 'Decode JWT' to analyze existing tokens. Each tab provides specific tools for the chosen operation.

2

Step 2: Configure JWT Settings

For generation: Choose HMAC algorithm (HS256, HS384, HS512), enter a strong secret key, and define your payload with claims like sub, exp, iat.

3

Step 3: Create or Input JWT

Generate: Click 'Generate JWT Token' to create your signed token. Decode: Paste an existing JWT token into the input field for analysis.

4

Step 4: Review & Use Results

Copy the generated token for use in your application headers, or review decoded header and payload information for validation.

Supported JWT Algorithms

Our tool supports the most commonly used HMAC-based algorithms for JWT signing

HS256

HMAC SHA-256

Most widely used algorithm, provides good security with 256-bit hash

Recommended for most applications requiring JWT authentication

HS384

HMAC SHA-384

Higher security variant using 384-bit hash for enhanced protection

Suitable for applications requiring stronger security measures

HS512

HMAC SHA-512

Strongest HMAC algorithm with 512-bit hash for maximum security

Best for high-security applications and sensitive data transmission

JWT Security Best Practices

  • Use strong, randomly generated secret keys (minimum 256 bits for HS256)
  • Always set appropriate expiration times (exp claim) to limit token lifetime
  • Never store sensitive information like passwords in JWT payload
  • Implement proper token refresh mechanisms for long-lived sessions
  • Validate JWT signatures on the server side before trusting claims
  • Use HTTPS to prevent token interception during transmission
  • Consider token blacklisting for logout and security breach scenarios
  • Regularly rotate secret keys in production environments

Standard JWT Claims

Predefined claim names that provide interoperability between JWT implementations

iss

Issuer

Identifies the principal that issued the JWT

sub

Subject

Identifies the principal that is the subject of the JWT

aud

Audience

Identifies the recipients that the JWT is intended for

exp

Expiration Time

Time after which the JWT expires (Unix timestamp)

nbf

Not Before

Time before which the JWT must not be accepted

iat

Issued At

Time at which the JWT was issued

jti

JWT ID

Unique identifier for the JWT

Common JWT Issues & Solutions

Invalid JSON in Payload

Ensure your payload is valid JSON format with proper quotes around strings and no trailing commas

Token Expired Error

Check the 'exp' claim value - it should be a future Unix timestamp. Update expiration time as needed

Signature Verification Failed

Verify you're using the correct secret key and algorithm that was used to sign the original token

Malformed JWT Token

JWT must have exactly 3 parts separated by dots (header.payload.signature). Check for missing or extra dots

JWT Examples

Simple user authentication token with basic user information and expiration

{
  "sub": "user123",
  "name": "John Doe",
  "email": "john@example.com",
  "iat": 1640995200,
  "exp": 1641081600
}