Last updated: March 2026
What Is a JWT Token Decoder?
A JWT Token Decoder parses JSON Web Tokens into their three components: header (algorithm and type), payload (claims and data), and signature. It helps developers debug authentication flows, inspect token contents, and verify expiration times without writing code.
Frequently Asked Questions
What is a JWT token?
A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication and authorization. It contains a header, payload (claims), and signature, each Base64URL-encoded and separated by dots.
Is it safe to paste my JWT here?
Yes. This tool runs entirely in your browser — your token is never sent to any server. However, never share JWTs publicly as they may contain sensitive information.
Can I verify the signature?
This tool decodes and inspects the token structure. For HMAC signatures, you can paste the secret to verify. For RSA/ECDSA, paste the public key.
What are common JWT claims?
iss (issuer), sub (subject), aud (audience), exp (expiration), iat (issued at), nbf (not before), and jti (JWT ID). Custom claims can contain any data.
How do I know if my token is expired?
The tool checks the exp (expiration) claim and shows whether the token is currently valid or expired, with a countdown or time-since-expiration display.