SummaryLog

JWT Decoder

Decode and inspect JSON Web Tokens. Nothing is sent to a server.

This JWT decoder splits a JSON Web Token into its three dot-separated parts and base64url-decodes the header and payload into readable, formatted JSON. The token is color-coded so you can see at a glance where the header, payload, and signature begin and end.

It also reads the standard exp and iat claims, showing you when the token expires and was issued in both absolute and relative time, plus an Expired or Valid badge. Use it to debug a 401 from an API, confirm which claims a backend issued, or check whether a token has already expired.

How to use

  1. Paste your JWT into the token box at the top of the page.
  2. Read the decoded Header and Payload, each shown as formatted JSON in its own panel.
  3. Check the Valid or Expired badge and the issued/expires times derived from the iat and exp claims.
  4. Click Copy next to any section to copy the header JSON, payload JSON, or raw signature.

FAQ

Is my token sent to a server?
No. Decoding happens entirely in your browser using JavaScript. The token is never uploaded, logged, or transmitted, which makes it safe to inspect tokens during debugging.
Does this verify the JWT signature?
No. This tool decodes and displays the token's contents but does not cryptographically verify the signature, because that requires your secret or public key. It is a decoder, not a validator.
Why does it say my token is invalid?
A JWT must have exactly three base64url-encoded parts separated by dots, and the header and payload must be valid JSON. A truncated, malformed, or non-JWT string will be rejected.
What do the colors mean?
The token is split into three colored segments: red for the header, purple for the payload, and cyan for the signature. The decoded Header and Payload panels use the same color accents.
How is the expiration time calculated?
It reads the exp claim, which is a Unix timestamp in seconds, converts it to a date, and compares it to your current time to show whether the token is still valid and how long until or since it expires.