Generated JWT Token
Decoded Token Details
Free JWT Generator & Token Creator Online
Create cryptographically signed JSON Web Tokens for authentication and authorization
Our free JWT Generator creates cryptographically signed JSON Web Tokens with custom payloads, claims, and expiration times. Support for HMAC-SHA algorithms (HS256, HS384, HS512), automatic claim injection (iat, exp, jti), and instant token preview. Perfect for developers building authentication systems, testing API security, or learning about token-based auth.
🔑 What is a JSON Web Token (JWT)?
A JSON Web Token (JWT, pronounced 'jot') is a compact, URL-safe token format defined by RFC 7519 for securely transmitting information between parties as a JSON object. JWTs consist of three Base64URL-encoded parts separated by dots: the Header (specifying the algorithm and token type), the Payload (containing claims — statements about the user and metadata), and the Signature (cryptographic hash ensuring the token hasn't been tampered with). JWTs are the industry standard for stateless authentication in modern web applications.
🛠️ How to Generate a JWT
- 1 Choose a signing algorithm — HS256 (recommended for most use cases), HS384, or HS512 for stronger security.
- 2 Set the token expiration time — from 1 hour for short-lived access tokens to 30 days for refresh tokens.
- 3 Enter your secret key — this is used to sign the token and must be kept secure. Use a strong, random string.
- 4 Define the payload as JSON — include claims like 'sub' (subject/user ID), 'name', 'role', and any custom data.
- 5 Toggle automatic claims: 'iat' (issued at timestamp) and 'jti' (unique token identifier) for enhanced security.
- 6 Click 'Generate JWT' to create your signed token with all configured options.
✨ Key Features
HMAC-SHA Algorithms
Sign tokens with HS256, HS384, or HS512 — industry-standard HMAC algorithms using the Web Crypto API for secure client-side signing.
Custom Claims & Auto-Claims
Define any custom payload claims plus automatic injection of standard claims like 'iat' (issued at) and 'jti' (unique ID).
Flexible Expiration
Set token expiry from 1 hour to 30 days, or create tokens with no expiration — perfect for different security requirements.
🎯 Common Use Cases
🔐 Authentication Systems
Generate JWTs for user authentication in web and mobile applications. Create access tokens with user identity claims, roles, and permissions for stateless session management.
🌐 API Authorization
Create bearer tokens for API authorization. Generate tokens with scoped permissions, resource access claims, and expiration times for secure API-to-API communication.
🧪 Testing & Development
Generate test JWTs for development environments. Create tokens with specific claims and expiration times to test authentication logic, middleware, and protected routes.
📚 Learning JWT
Understand JWT structure hands-on. Generate tokens, inspect the decoded header and payload, and learn how signing algorithms create tamper-proof tokens.
💡 JWT Security Best Practices
- Use strong, random secret keys — at least 256 bits (32 characters) for HS256. Never use simple passwords or predictable strings.
- Set short expiration times for access tokens (15-60 minutes) and longer times for refresh tokens (7-30 days).
- Always include the 'exp' (expiration) claim — tokens without expiration remain valid indefinitely if compromised.
- Never store sensitive data (passwords, credit card numbers) in JWT payload — the payload is Base64-encoded, not encrypted.
- Use the 'jti' (JWT ID) claim to implement token revocation lists for additional security.
- Rotate your signing keys periodically and implement key versioning to minimize the impact of key compromise.
❓ Frequently Asked Questions
Is it safe to generate JWTs in the browser?
Yes, for development and testing purposes. This tool uses the Web Crypto API to sign tokens entirely in your browser — your secret key never leaves your device. However, for production systems, always generate tokens server-side where the secret key is stored securely.
What's the difference between HS256, HS384, and HS512?
All three are HMAC algorithms using SHA hash functions. HS256 uses SHA-256 (256-bit output), HS384 uses SHA-384 (384-bit), and HS512 uses SHA-512 (512-bit). HS256 is the most commonly used and provides adequate security for most applications. HS384/HS512 offer progressively stronger security at the cost of slightly larger token sizes.
How long should my secret key be?
For HS256, use at least 32 characters (256 bits). For HS384, use at least 48 characters (384 bits). For HS512, use at least 64 characters (512 bits). Use a cryptographically random string generator — avoid dictionary words, predictable patterns, or personal information.
What claims should I include in a JWT?
Standard claims include: 'sub' (subject — usually user ID), 'exp' (expiration time), 'iat' (issued at), 'iss' (issuer), 'aud' (audience), and 'jti' (JWT ID). Add custom claims for role, permissions, or application-specific data. Keep the payload minimal to reduce token size.
Can I decode a JWT generated with this tool?
Yes! Use our JWT Decoder tool to decode and inspect the header, payload, and signature of any JWT. The header and payload are Base64URL-encoded, so they can be decoded without the secret key. The signature, however, can only be verified with the original signing key.