🔑 JWT Decoder
Decode and inspect JWT tokens instantly — view header, payload, and signature. Verify signatures with your secret. Free online JWT decoder — nothing sent to any server.
How to Use
1
Paste your JWT
Copy your JWT token (starting with eyJ) and paste it into the input field.
2
Click Decode
Press Decode to instantly split and decode all three parts: header, payload, and signature.
3
Inspect the token
Read the decoded JSON, check expiration dates, algorithm, and any custom claims in the payload.
Frequently Asked Questions
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token used for authentication and information exchange. It consists of three Base64URL-encoded parts separated by dots: Header.Payload.Signature.
Is it safe to paste my JWT here?
Yes. This tool runs 100% in your browser — your token is never sent to any server. However, never share JWTs containing sensitive data in public forums or untrusted tools.
Can this tool verify the JWT signature?
No. Signature verification requires the secret key or public key used to sign the token, which only your server knows. This tool decodes and displays the token contents only.
What does "exp" mean in the payload?
"exp" is the expiration time as a Unix timestamp (seconds since Jan 1, 1970). This tool automatically converts it to a human-readable date and shows whether the token has expired.
What is the difference between "iat" and "nbf"?
"iat" (issued at) is when the token was created. "nbf" (not before) is the earliest time the token is valid. Both are Unix timestamps.
Guide : Décodeur JWT
Qu'est-ce que c'est ?
Le Décodeur JWT décompose les JSON Web Tokens en leurs trois parties : en-tête, charge utile et signature — et affiche les claims de manière lisible.
Il est indispensable pour déboguer les problèmes d'authentification, vérifier l'expiration des tokens et inspecter les permissions encodées.
Comment utiliser
- Collez votre JWT (format
xxxxx.yyyyy.zzzzz) dans le champ d'entrée. - L'en-tête et la charge utile sont décodés et affichés en JSON formaté.
- Vérifiez les claims comme
exp,iat,subetiss. - Notez que la vérification de signature nécessite la clé secrète.
Conseils professionnels
- Vérifiez toujours
expcôté serveur — un JWT décodable n'est pas forcément valide. - Ne mettez jamais de données sensibles dans la charge utile JWT — elle n'est qu'encodée, pas chiffrée.