Does this verify the signature?
No. It only decodes header and payload so you can inspect claims.
jfmt.dev
JWT Decoder
Paste a JSON Web Token to read header and payload as JSON. Useful for debugging auth, but this page does not verify signatures.
JSON formatter
Input
Output · preview.json
{ }
Run a tool to see a polished result here
Decode vs verify
Decoding only base64-reads the token. Signature verification needs the key and does not happen here — never paste production secrets into any online tool, including this one. Processing stays on this device.
Related tools
FAQ
Is my token uploaded?
No. Decoding runs in the browser.
What if the token is malformed?
You get an error in the editor. Fix the three base64url segments and try again.