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JWT Decoder

Decode and inspect JSON Web Tokens (JWT). View header, payload, and signature details with expiration checking and claim inspection.

Decode JWT headerDecode JWT payloadSignature info & algorithmExpiration checkClaim inspectionPretty-print JSON

JWT Token

How to Use the JWT Decoder

  1. 1Paste your JWT token into the input area or click "Load Sample" to try a demo token
  2. 2The tool instantly decodes and displays the header, payload, and signature
  3. 3Review the Header panel (red) for algorithm and token type information
  4. 4Inspect the Payload panel (purple) for claims and decoded timestamps
  5. 5Check the expiration status indicator to see if the token is still valid
  6. 6Click "Copy" on any panel to copy the decoded data to your clipboard

Frequently Asked Questions

What is a JSON Web Token (JWT)?

A JWT is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three Base64URL-encoded parts separated by dots: a header (algorithm & type), a payload (claims/data), and a signature for verification.

Is it safe to decode JWTs in the browser?

Yes! This tool runs entirely client-side — your token never leaves your browser or gets sent to any server. However, remember that JWT payloads are only Base64-encoded, not encrypted, so never put sensitive secrets in JWT payloads.

Can this tool verify JWT signatures?

This tool decodes and displays the signature, but full signature verification requires the secret key (for HMAC algorithms) or the public key (for RSA/ECDSA). Without the key, you can inspect the token contents but cannot confirm authenticity.

What do the iat, exp, and nbf claims mean?

"iat" (Issued At) is when the token was created, "exp" (Expiration Time) is when it expires, and "nbf" (Not Before) is the earliest time the token should be accepted. All are Unix timestamps (seconds since January 1, 1970).

Why does my JWT show as expired?

The tool compares the "exp" claim against your current system time. If the current time is past the expiration timestamp, the token is marked as expired. Expired tokens should be refreshed or re-issued by the authentication server.

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