JWT Decoder
Decode and inspect JSON Web Tokens. Paste a JWT to view the header, payload, and expiry status. No signature verification — runs entirely in your browser.
Frequently Asked Questions
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token with three Base64url-encoded parts: a header (algorithm), a payload (claims like user ID and expiry), and a signature. They are used for authentication and information exchange.
Does this tool verify the JWT signature?
No. Signature verification requires the secret key. This tool only decodes the header and payload so you can inspect the contents — it does not validate whether the token is authentic or unexpired.
Is it safe to paste a JWT here?
JWTs containing sensitive user data should not be pasted into online tools. This tool processes everything in your browser and sends nothing to a server, but if the JWT is active and sensitive, use a private environment instead.
Is my data private?
Yes — completely. Everything runs locally in your browser. Nothing is sent to any server, and nothing is retained after you close the tab.