JSON Web Token vs Keycloak: What are the differences?

Both JWT and Keycloak are technologies used in web development for authentication and authorization purposes. Let's explore the key differences between them.

1. Scalability: One key difference between JWT and Keycloak lies in their scalability. JWT is a lightweight and stateless authentication protocol that can be easily implemented and used with different programming languages and frameworks. It is suitable for small to medium-sized applications where scalability is not a major concern. On the other hand, Keycloak is a more robust and feature-rich identity and access management system that provides centralized authentication and authorization services. It offers features like user management, single sign-on, and social login integration, making it suitable for large-scale applications with complex security requirements.

2. Token Generation and Authentication: JWT is a token-based authentication protocol where a JSON-encoded token is generated by the server and sent to the client. The client includes this token in subsequent requests to authenticate itself with the server. The server verifies the token's integrity by checking its digital signature, ensuring that it has not been tampered with. Keycloak, on the other hand, uses a session-based authentication approach. When a user logs in, Keycloak generates a session cookie that is stored on the client-side. This cookie is sent along with every request to the server, allowing Keycloak to authenticate the user based on the session information stored on the server.

3. User Management: Keycloak offers comprehensive user management capabilities, allowing administrators to create, manage, and authenticate users. It provides features like user registration, password reset, and user role management out of the box. JWT, on the other hand, does not provide built-in user management functionality. It is primarily a mechanism for securely transmitting authentication and authorization data between parties. User management needs to be implemented separately when using JWT.

4. Integration and Compatibility: JWT is a standard-based protocol and can be easily integrated into existing applications and systems. It is widely supported by various programming languages and frameworks, making it a popular choice for cross-platform development. Keycloak, while also compatible with standard protocols like OpenID Connect and SAML, requires additional setup and configuration to integrate with existing applications. It provides its own user interface and APIs for managing authentication and authorization, which may require more effort to integrate into existing systems.

5. Security Features: Keycloak provides additional security features like two-factor authentication, brute-force protection, and fine-grained access control policies. It allows administrators to define complex security rules based on user roles, groups, and attributes. JWT, being a lightweight protocol, does not provide these advanced security features natively. Security measures like two-factor authentication and access control policies need to be implemented separately in the application when using JWT.

6. Deployment Options: Keycloak can be deployed as a stand-alone identity server or integrated into existing applications as a library. It provides options for high availability and clustering to ensure scalability and fault tolerance. JWT, on the other hand, can be easily integrated into any application or service that supports the JSON format. It does not require any specific deployment options and can be used with different architectures, including microservices and serverless environments.

In summary, JWT offers a lightweight and decentralized approach to authentication, suitable for scenarios where simplicity and scalability are priorities, while Keycloak provides a comprehensive IAM solution with features like user federation, role-based access control, and social login integration, ideal for applications requiring robust identity management capabilities.