JWT Decoder
Decode JWT header and payload JSON without claiming to verify the signature.
Processing happens locally in your browser. Your files and inputs are not uploaded to our servers.
How to use JWT Decoder
- Paste a compact JWT or load the safe example token.
- Decode the header and payload into formatted JSON.
- Inspect and copy individual sections; verify signatures in your trusted application.
What JWT Decoder does
A JSON Web Token usually contains Base64URL-encoded header and payload sections plus a signature section. Reading those sections reveals claims but does not prove who created the token.
Examples
- Inspect an `exp` claim to see the encoded expiration time.
- Pretty-print a JWT header to identify the declared algorithm.
- Copy a decoded payload while keeping the signature segment visible.
Frequently asked questions
Is my input uploaded?
No. This tool processes its input locally in your browser. Normal page requests do not include the contents you enter or select.
Does decoding verify the JWT signature?
No. Signature verification requires the correct trusted key and algorithm policy. This tool only decodes token sections.
Will it work in every browser?
The tool uses modern browser APIs. Current Chromium, Firefox, and Safari releases provide the best support; the page displays a clear error when a required capability is unavailable.