JWT Decoder
Paste any JSON Web Token to instantly decode the header, payload, and claims. Check expiry, issuer, subject, and more. Your token never leaves your browser.
Paste a JWT token above to decode it
Or click "Load sample token" to see an example
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used to securely transmit information between parties. It consists of three base64url-encoded sections separated by dots:
JWTs are widely used in API authentication — when you log in to an app, a JWT is issued and sent with every subsequent request to prove your identity. The payload is only base64-encoded, not encrypted, so never put sensitive data (passwords, secrets) in a JWT payload.
Frequently Asked Questions
What is a JWT token?
A JSON Web Token (JWT) is a compact token used for authentication and authorization. It has three parts: a header (algorithm), a payload (claims/user data), and a signature. It's base64url encoded and separated by dots.
Is it safe to paste my JWT here?
Yes — this decoder runs entirely in your browser. Your token is never sent to any server. That said, avoid pasting live production tokens with sensitive data into any online tool as a security best practice.
Why can't you verify the signature?
Signature verification requires the secret key or public key used to sign the token. That key is never in the token itself. This tool decodes and inspects the header and payload, which is what you need for debugging.
What are JWT claims?
Claims are key-value pairs in the payload. Standard ones include: iss (issuer), sub (subject/user ID), aud (audience), exp (expiry timestamp), iat (issued at), and nbf (not before). Custom claims can include roles, permissions, or any application data.
What does 'token expired' mean?
The exp claim in the payload is a Unix timestamp. If the current time is past that timestamp, the token is expired and will be rejected by the server. You need to refresh or re-issue the token.
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