A JWT, short for JSON Web Token, is a small piece of text that websites use to remember who you are after you log in. It looks like three blocks of letters separated by dots. This free JWT decoder reads those blocks for you, right in your browser.
Paste your token in the box and press Decode. The tool shows the header first. The header usually tells you which signing method was used, for example HS256 or RS256. Then it shows the payload, which holds the real data: a user id, a name, roles, and often an expiry time.
The third block is the signature. This tool only decodes the token. It does not check the signature, because checking needs the secret key, and you should never paste a secret key into a website. Decoding is safe here because nothing leaves your device: the whole job runs in your own browser.
One field deserves attention: exp. It is the expiry time, written as seconds since 1970. If the date shown is in the past, the token is expired and a server should reject it. The tool prints this plainly so you do not have to convert the number yourself.
Developers use this decoder to debug login problems. If a user says they cannot access a page, decode their token and check the user id, the roles, and the expiry. Most login bugs turn out to be a wrong role or an expired token, and both are visible in seconds.
A warning that matters: a JWT is not encrypted by default. Anyone who holds the token can decode it, exactly like this tool does. So never store passwords, credit card numbers, or other secrets inside a token. Keep tokens short-lived, send them only over HTTPS, and store them safely.
Try it now with the sample token already in the box. Then paste a real token from your own app and check what it carries. It is free, it needs no sign-up, and your token never leaves your browser.