Back to Home

JWT Parser Online

Securely decode, verify, and generate JWTs (JSON Web Tokens) on the client side, protecting your data privacy.

Encoded

Paste your JWT here...

Decoded

Header

Algorithm & Token Type
{}

Payload

Data
{}

Signature

HMACSHA256(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload),
  your-256-bit-secret
)

What is a JWT (JSON Web Token)?

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the HMAC algorithm) or a public/private key pair using RSA or ECDSA.

Structure of a JWT

JWTs consist of three parts separated by dots (.), which are:

  • Header: Typically consists of two parts: the type of the token, which is JWT, and the signing algorithm being used, such as HMAC SHA256 or RSA.
  • Payload: Contains the claims. Claims are statements about an entity (typically, the user) and additional data. E.g., user ID, roles, expiration time (exp).
  • Signature: To create the signature part you have to take the encoded header, the encoded payload, a secret, the algorithm specified in the header, and sign that to verify that the sender of the JWT is who it says it is and to ensure that the message wasn't changed along the way.

How to decode and verify JWT online?

Paste your JWT string into the "Encoded" text box on the left. The system will automatically split it, decode it using Base64Url, and clearly display the JSON content of the Header and Payload on the right. If you know the Secret Key used for signing, you can enter it in the verification box at the bottom right. The system will calculate the signature locally and verify the validity of the Token.

Is JWT secure?

The signature mechanism of JWT ensures data integrity (tamper-proof), but it is NOT encrypted by default (Base64 encoding can be decoded by anyone). Therefore, never put passwords or sensitive personal information in the JWT Payload. As long as the server's Secret Key is kept safe and a reasonable expiration time is set, JWT is highly secure for authentication and authorization scenarios.