Does decoding verify the token's signature?

No, this decodes the header and payload to let you inspect the contents — it doesn't verify the signature, which would require the signing key.

Is a JWT's payload encrypted?

No, it's just Base64-encoded, not encrypted — anyone with the token can read its contents, which is exactly why sensitive data shouldn't be stored in a JWT payload.

Is my token uploaded anywhere when I decode it?

No, decoding happens locally in your browser — your token isn't sent anywhere.

Does JWT Decoder upload my files to a server?

No. JWT Decoder runs entirely in your browser using on-device processing, your files never leave your device.

JWT Decoder

Decode a JSON Web Token's header and payload.

Runs in your browser

JWT

Decodes the header and payload only — the signature isn't verified, since that requires the issuer's secret or public key. Runs entirely in your browser.

About this tool

A JWT's header and payload are Base64-encoded but not encrypted, meaning the data inside is readable by anyone with the token — decoding it is often necessary for debugging authentication issues or inspecting what claims a token actually carries. This tool decodes a JSON Web Token's header and payload, letting you inspect a token's contents directly without writing a decoding script yourself.

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