JWT Generator
Generate signed JWT tokens with custom header, payload, and secret key.
β For testing only β never expose real secrets.
About this tool
JWT Generator creates signed JSON Web Tokens (JWTs) directly in your browser with custom header, payload, and secret key. JWTs are widely used in modern web applications for stateless authentication and authorization, allowing servers to verify the token's authenticity and integrity without querying a database. The tool supports HS256 (HMAC with SHA-256) signing, the most common symmetric key algorithm for JWT generation.
Enter or customize the header and payload JSON objects, supply your secret key, and click Generate to create a cryptographically signed token. The tool uses the Web Crypto API to compute the HMAC-SHA256 signature in real-time, ensuring your secret never leaves your browser. The output token consists of three Base64-encoded parts separated by dots: header, payload, and signature. You can immediately copy the generated token for use in API requests, headers, or application configuration.
This generator is ideal for testing authentication flows, generating test tokens for development, and learning how JWT signing works under the hood. Always use a strong, unique secret key in production environments, and never share or hardcode secrets in client-side code. For production systems, generate JWTs on a secure backend server with proper key management practices.
Frequently Asked Questions
Code Implementation
import jwt
import datetime
secret = "your-secret-key"
# Create a JWT (HS256)
payload = {
"sub": "user123",
"name": "Alice",
"iat": datetime.datetime.utcnow(),
"exp": datetime.datetime.utcnow() + datetime.timedelta(hours=1),
}
token = jwt.encode(payload, secret, algorithm="HS256")
print(token)
# Decode and verify
try:
decoded = jwt.decode(token, secret, algorithms=["HS256"])
print(decoded) # {'sub': 'user123', 'name': 'Alice', ...}
except jwt.ExpiredSignatureError:
print("Token has expired")
except jwt.InvalidTokenError:
print("Invalid token")Comments & Feedback
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