JWT Security Validator
Decode, validate, and analyze JSON Web Tokens for security vulnerabilities. Check algorithm, expiration, claims, and identify common JWT security issues.
Paste a JWT token to analyze its security
About JWT Security
JWTs should always have an expiration (exp) claim
Avoid 'none' algorithm which allows forged tokens
Use asymmetric algorithms (RS256/ES256) for distributed systems
Why Validate JWTs?
JWTs are widely used for authentication. Misconfigurations can lead to security vulnerabilities like algorithm confusion attacks, missing expiration, or weak signatures.
Frequently Asked Questions
What is a JWT?
JSON Web Token (JWT) is a compact, URL-safe means of representing claims between two parties, commonly used for authentication and information exchange.
What is algorithm confusion?
Algorithm confusion attacks exploit JWT libraries that accept 'none' algorithm or confuse RSA/HMAC algorithms, allowing forged tokens.
Should I use symmetric or asymmetric algorithms?
Asymmetric algorithms (RS256, ES256) are safer for distributed systems as only the issuer needs the private key. HMAC requires sharing the secret.
What claims should JWTs have?
At minimum: exp (expiration), iat (issued at), and iss (issuer). Consider nbf (not before), aud (audience), and sub (subject) for additional security.