JWT Token Generator

What is JWT?

JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. JWTs consist of three parts: header, payload, and signature. They are commonly used for authentication and authorization in web applications and APIs.

Our free JWT Token Generator helps you create JWT tokens by encoding header and payload data. Note that this is a simplified generator for demonstration. For production use, use proper JWT libraries that implement HMAC-SHA256 or RSA signatures correctly.

JWT Structure

JWTs consist of three parts separated by dots:

• Header: Algorithm and token type (e.g., HS256, RS256)
• Payload: Claims (user data, expiration, etc.)
• Signature: Verifies token authenticity

Format: header.payload.signature

Common JWT Claims

• sub (subject): User ID or identifier
• iat (issued at): Token creation timestamp
• exp (expiration): Token expiration timestamp
• iss (issuer): Token issuer
• aud (audience): Token audience

Best Practices

• Use Secure Algorithms: Use HS256 or RS256, avoid none algorithm
• Set Expiration: Always include exp claim for token expiration
• Protect Secret Keys: Keep secret keys secure and never expose them
• Validate Tokens: Always validate tokens server-side
• Use HTTPS: Transmit JWTs only over HTTPS
• Store Securely: Store JWTs securely (httpOnly cookies recommended)

FAQs

What is JWT used for?

JWTs are used for authentication and authorization, allowing stateless authentication in web applications and APIs.

How long should JWT tokens last?

JWT expiration depends on use case. Access tokens typically last 15 minutes to 1 hour, while refresh tokens can last days or weeks.

Are JWTs secure?

JWTs are secure when properly implemented with strong algorithms, secure secret keys, and proper validation. Always use HTTPS.

Can I decode JWT tokens?

Yes, JWT header and payload are base64-encoded and can be decoded. The signature must be verified to ensure authenticity.

What's the difference between HS256 and RS256?

HS256 uses a shared secret key, while RS256 uses RSA public/private key pairs. RS256 is better for distributed systems.