JWT Claims Validator
Validate JWT token claims including expiry and issuer.
About this tool
JSON Web Tokens (JWT) are widely used for authentication and data exchange in modern web applications, but their claims must be validated to ensure security and correctness. The JWT Claims Validator allows you to decode and verify JWT claims such as expiry (exp), issued-at (iat), issuer (iss), audience (aud), and other standard claims without needing command-line tools or server-side authentication. This is essential for developers debugging token issues, security professionals auditing tokens, and DevOps engineers managing API infrastructure.
To use the validator, paste your JWT token into the input field and the tool instantly decodes and displays all claims in a readable format. You can see the token's signature validity, expiry status, and all custom claims at a glance. The tool checks whether the token has expired and highlights critical information like issuer and audience, making it easy to spot misconfigurations or tampering. Everything runs entirely in your browser, so your tokens never leave your device.
JWT validation is crucial for preventing unauthorized access and detecting compromised or malformed tokens. By checking claims regularly during development and troubleshooting, you can catch authentication issues early and avoid production outages. This tool is invaluable for anyone working with REST APIs, microservices, OAuth flows, or single sign-on (SSO) systems where JWTs are the standard authentication mechanism.
Frequently Asked Questions
Code Implementation
import jwt # pip install PyJWT
import datetime
SECRET = "your-256-bit-secret"
# Create a JWT (HS256)
payload = {
"sub": "user123",
"iss": "https://myapp.com",
"aud": "https://api.myapp.com",
"iat": datetime.datetime.utcnow(),
"exp": datetime.datetime.utcnow() + datetime.timedelta(hours=1),
"role": "admin",
}
token = jwt.encode(payload, SECRET, algorithm="HS256")
print("Token:", token)
# Decode and verify a JWT
try:
decoded = jwt.decode(
token,
SECRET,
algorithms=["HS256"],
audience="https://api.myapp.com",
)
print("Subject:", decoded["sub"])
print("Role:", decoded["role"])
except jwt.ExpiredSignatureError:
print("Token has expired")
except jwt.InvalidTokenError as e:
print("Invalid token:", e)
# Decode without verification (inspect only β never trust for auth)
header = jwt.get_unverified_header(token)
print("Algorithm:", header["alg"])Comments & Feedback
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