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JWT Debugger

Decode and debug JSON Web Tokens (JWT). Inspect header, payload, and verify signatures instantly.

Encoded Token
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Header (Algorithm & Metadata)
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Payload (Data & Claims)
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Verify Signature

Your secret key is processed entirely in the browser and never leaves your device.

About JWT Debugger

Our online JWT Debugger allows you to instantly decode any JSON Web Token. Beyond simple decoding, you can now verify signatures locally. Simply paste your token and secret key to ensure the token hasn\'t been tampered with.

Frequently Asked Questions

What is a JSON Web Token (JWT)?

JWT is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object.

How does verification work?

You must provide the secret key (for HMAC algorithms like HS256) used to sign the token. We calculate the signature locally in your browser and compare it to the one in the token.

Which algorithms are supported?

Currently, we support HMAC-based verification (HS256, HS384, HS512). Public/Private key verification (RS256) functionality is planned for a future update.

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