Is my JWT sent to a server?

Absolutely not. The token is decoded entirely in your browser using JavaScript. It never leaves your device.

Does this tool verify the JWT signature?

No. Decoding only reads the header and payload. Signature verification requires the secret key, which should never be shared with any tool.

JWT Decoder

Browser-based

Paste a JWT to decode and display its header and payload sections. Decoding is not verification — always handled client-side, never sent to any server.

Processed 100% in your browser â€” your file never leaves this device.

How we prove it

Free forever
No signup
Works offline
Ad-free

About JWT Decoder

Look inside a JSON Web Token to see exactly what it contains. Paste a JWT and instantly read its header and payload claims, which is useful when debugging authentication flows or verifying what data an application has attached to a token. Decoding happens entirely in your browser — your token never leaves your device, and signatures are never touched.

How to use

1
Paste your JWT into the input field.
2
The header and payload are decoded and displayed instantly.

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