JWT Authentication Definition

KZero Staff
Jul 27, 2023

What is JWT Authentication?

JSON Web Token (JWT) Authentication is a means of tracking authentication information in a stateless web application. After a user successfully authenticates to the application, a JWT is generated and stored on the client side. The client will include the token with each subsequent request, enabling the server to verify that the user has been successfully authenticated without tracking authentication state itself.

Structure of a JWT

A JSON Web Token is designed to summarize authentication information in a token that the server can easily consume and validate. The JWT has three main parts:

  • Header: The header specifies the type of token (JWT) and the digital signature algorithm used for verification.
  • Payload: The payload contains the claims about the user’s identity and other relevant information. These claims verify that the user was authenticated and contain the information needed to verify that they are authorized to access the web app.
  • Signature: A JWT is signed by the party who authenticated the user and generated the JWT. This proves that the token is authentic and that it has not been modified.

These three sections of the JWT are encoded using the Base64 algorithm. These encoded values are then concatenated using periods to create a single string.

How Does JWT Authentication Work?

JWTs enable stateless authentication tracking in a web application. The key steps of the JWT authentication process include:

  • Authentication: The user authenticates to the system using a password, biometrics, etc.
  • Token Issuance: After authenticating the user’s identity, the server generates a JWT that includes the user’s identity and the privileges granted to them.
  • Token Storage: The server sends the JWT to the client, which stores it locally on their device.
  • Authenticated Requests: For subsequent requests, the JWT is included in the HTTP headers of the request.
  • Server-Side Verification: When the server receives a request, it will validate the JWT. If it passes, then the server will process the request.
  • Expiration: Every JWT has a built-in expiration date. After this point, it cannot be used to authenticate a user.

Benefits of JWT Authentication

JWTs provide several benefits for authentication, including:

  • Stateless: JWT authentication is stateless, meaning that the server doesn’t need to track session and authentication data.
  • Self-Contained: JWTs are self-contained, including all of the information needed for authentication and authorization. This reduces the size and number of database queries that a web application needs to perform.
  • Scalability: Since JWTs are self-contained, they are a very scalable authentication system. No server-side resources are dedicated to tracking authentication and session data.
  • Compactness: JWTs compactly store authentication information. This reduces their size on disk and bandwidth utilization.


JWT authentication is a stateless authentication mechanism for web applications. Authentication and authorization data is contained within a digitally signed token that is stored by the client and included in each address. This enables a server to validate the user’s access without the need for the user to log in with each request or for the server to track user sessions and authentication status.

KZero Staff

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