Question 1

What is a JWT?

Accepted Answer

A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication and information exchange. It consists of three parts: header, payload, and signature.

Question 2

Does this tool verify the signature?

Accepted Answer

This tool decodes and displays the JWT parts. Signature verification requires the secret key or public key, which is not performed here for security reasons.

Question 3

Is my JWT sent to a server?

Accepted Answer

No. All decoding happens locally in your browser. Your token never leaves your device.

Question 4

What claims does it check?

Accepted Answer

It displays all claims and highlights standard ones like exp (expiration), iat (issued at), nbf (not before), sub (subject), and iss (issuer).

Question 5

Can I use this with expired tokens?

Accepted Answer

Yes. The tool decodes any valid JWT structure regardless of expiration. It will show the expiration status clearly.

Question 6

What JWT algorithms are supported?

Accepted Answer

The decoder works with any JWT regardless of algorithm (HS256, RS256, ES256, etc.) since it only decodes the base64 content.

JWT Debugger

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