JWT (JSON Web Token)
JSON Web Token is an open, industry-standard RFC 7519 method for representing claims securely between two parties. It is widely utilized in modern web development for Authentication and Authorization processes. Because JWT is compact and self-contained, it is particularly useful for Single-Sign-On (SSO) scenarios and API-Security.
Structure of a JWT
A JWT typically consists of three parts separated by dots: a Header, a Payload, and a Signature. The Header usually defines the token type and the hashing algorithm, such as HMAC SHA256 or RSA. The Payload contains the claims, which are statements about the user and additional metadata. The Signature is created by taking the encoded header, the encoded payload, a secret, and the algorithm specified in the header to sign the package. This ensures the integrity of the token. For a deep dive into the technical implementation, refer to the documentation at JWT.io and the Auth0 Guide.
Usage in Web Applications
In a typical Stateless architecture, once a user logs in, the server returns a JWT. The client stores this token (often in Local-Storage or a Cookie) and sends it in the HTTP-Header for subsequent requests. This removes the need for the server to maintain Session-Management state, improving scalability.