JSON Web Token Validator

To Validate a JSON Web Token: Select the signing algorithm, enter your secret key or public/private key pair, then paste your JWT in the encoded field on the left.

To Generate a JSON Web Token: Choose the signing algorithm, configure your header and payload in JSON format, then provide or generate the appropriate signing key.

What is a JWT?
A JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three parts: a header (algorithm and token type), a payload (claims/data), and a signature (verification). JWTs are commonly used for authentication and information exchange in modern web applications.

How JWT Validation Works
The server validates a JWT by recomputing the signature using the header and payload, then comparing it with the signature in the token. If they match, the token is authentic and hasn't been tampered with. This allows stateless authentication without server-side session storage.

Advantages of JWT
    • Stateless authentication—no server-side session storage required
    • Scalable across multiple services and microarchitectures
    • Self-contained—carries all necessary information in the payload

Limitations of JWT
    • Cannot be revoked without additional infrastructure (blacklisting)
    • Payload is Base64-encoded, not encrypted—never store sensitive data
    • Token size increases with payload data

JWT has become one of the most widely adopted standards for API authentication and authorization in distributed systems.