JWT Encoder

Create and sign JWT tokens with custom payload and secret

⚠️ Keep your secret key secure. Never share it publicly.

⚠️ Note: This is a simplified JWT encoder for demonstration. For production use, implement proper HMAC signing with a crypto library like crypto-js or use a backend service.

What is a JWT Encoder?

A JWT Encoder is a powerful tool that creates and signs JSON Web Tokens with custom payload data and secret keys. It enables developers to generate secure authentication tokens with custom claims, expiration times, and signing algorithms (HS256, HS384, HS512) for testing, development, and learning purposes.

Token CreationHMAC SigningCustom Claims

Why Use JWT Encoder?

  • ✓
    Instant Token GenerationCreate signed JWT tokens in real-time as you type.
  • ✓
    Multiple AlgorithmsSupport for HS256, HS384, and HS512 signing.
  • ✓
    Quick Claim AdditionAdd exp, iat, nbf claims with one click.
  • ✓
    Visual Token PartsSee header, payload, and signature separately.

How to Use

Create your JWT token in four simple steps

01
🔐

Select Algorithm

Choose your signing algorithm: HS256 (most common), HS384, or HS512 based on your security needs.

02
📝

Customize Payload

Add your custom claims like user ID, roles, permissions, and expiration time. Use quick buttons to add standard claims.

03
🔑

Enter Secret Key

Provide your secret key for signing. Use a strong, random key (at least 256 bits for HS256).

04
📋

Copy Token

Your JWT token is generated automatically. Copy it and use it in your application for authentication.

HMAC Algorithms

🥉

HS256

HMAC with SHA-256 hash function. Most widely used and provides excellent security for most applications. Requires 256-bit (32-byte) secret key.

256-bitFast
🥈

HS384

HMAC with SHA-384 hash function. Provides stronger security than HS256 with moderate performance impact. Requires 384-bit (48-byte) secret key.

384-bitMedium
🥇

HS512

HMAC with SHA-512 hash function. Highest security level with larger signature size. Requires 512-bit (64-byte) secret key.

512-bitSlower

Standard JWT Claims

Essential fields for your JWT payload

👤

Subject

Required
sub

The subject of the token, typically the user ID or username that identifies who the token represents.

⏰

Expiration

Required
exp

Unix timestamp when the token expires. Critical for security—always set an expiration time.

📅

Issued At

iat

Unix timestamp when the token was created. Useful for tracking token age and debugging.

🚫

Not Before

nbf

Token is not valid before this Unix timestamp. Used for delayed token activation.

🏢

Issuer

iss

Identifies who created and signed the token (e.g., your authentication server domain).

🎯

Audience

aud

Identifies the recipients that the JWT is intended for (e.g., your API domain).

Common Use Cases

🧪

API Testing

Generate test tokens for API authentication during development and testing.

🎓

Auth Learning

Understand how JWT tokens are structured and signed in authentication systems.

🎭

Mock Tokens

Create mock tokens with specific claims for frontend development without backend.

🐛

Token Debugging

Generate tokens with different claims to test your token validation logic.

Security Best Practices

Critical security guidelines for JWT token creation

🔑

Use Strong Secret Keys

Generate cryptographically random secret keys with sufficient length (at least 256 bits for HS256). Never use predictable keys like 'secret' or 'password'. Store keys securely using environment variables or key management services.

⏱️

Always Set Expiration

Every JWT must have an 'exp' claim. Use short expiration times (15-60 minutes) for access tokens. Implement refresh tokens for long-lived sessions. Expired tokens should be rejected by your server.

📦

Minimize Payload Data

Keep JWT payloads small—only include essential claims. Never store passwords, credit card numbers, or sensitive personal data. Remember: JWTs are encoded, not encrypted, so anyone can read the payload.

🛡️

Use Production Libraries

This tool is for learning and testing only. For production, use established libraries like jsonwebtoken (Node.js), PyJWT (Python), or jose (JavaScript) that implement proper cryptographic signing.

JWT Token Structure

1

Header (Red)

Algorithm and token type

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
.
2

Payload (Purple)

Claims and user data

eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
.
3

Signature (Blue)

HMAC signature for verification

SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Why Choose Our JWT Encoder

⚡

Real-Time Generation

Tokens generated instantly as you type

🔐

Multiple Algorithms

HS256, HS384, HS512 support

⏰

Quick Claims

Add exp, iat, nbf with one click

👁️

Visual Breakdown

See header, payload, signature separately

📋

Copy Anywhere

Copy full token or individual parts

🆓

No Registration

Free and unlimited usage

🔒

Client-Side Only

All processing in your browser

📱

Mobile Friendly

Works on all devices

Explore Other Tools

🔍

JWT Decoder

Decode and inspect existing JWT tokens to view their contents.

🔄

Base64 Converter

Encode and decode Base64 strings used in JWT token parts.

🔑

Hash Generator

Generate secure hashes for JWT secret keys and signatures.

✨

JSON Formatter

Format and validate JSON data for JWT payloads.

Frequently Asked Questions

Common questions about JWT token creation and encoding.

A JWT Encoder is a tool that creates and signs JSON Web Tokens (JWT) with custom payload data and a secret key. It generates tokens that can be used for authentication, authorization, and secure data exchange in web applications.
To create a secure JWT: 1) Use a strong, random secret key (at least 256 bits for HS256), 2) Add an expiration time (exp claim) to limit token lifetime, 3) Include only necessary claims in the payload, 4) Never store sensitive data like passwords in the token, and 5) Always use HTTPS when transmitting tokens.
These are HMAC (Hash-based Message Authentication Code) algorithms with different hash functions: HS256 uses SHA-256 (256-bit hash), HS384 uses SHA-384 (384-bit hash), and HS512 uses SHA-512 (512-bit hash). Higher numbers provide stronger security but require more processing power. HS256 is the most commonly used and provides sufficient security for most applications.
This tool is designed for learning, testing, and development purposes. For production applications, use established JWT libraries like jsonwebtoken (Node.js), PyJWT (Python), or jose (JavaScript) that implement proper cryptographic signing and verification.
Common claims include: sub (user ID), exp (expiration time - required for security), iat (issued at time), iss (issuer), aud (audience), and custom claims like user roles, permissions, or email. Keep the payload small to reduce token size and avoid storing sensitive information.