Authentication verifies a user’s identity before granting access to a system. Different authentication methods are suited for different use cases.

Types of Authentication

• JWT (JSON Web Token)
• Session & Cookies
• API Key
• OAuth 2.0

Authentication Choices

For APIs (RESTful, Microservices, Mobile Apps)

• Use JWT (JSON Web Token) for stateless authentication, eliminating session storage and allowing scalable API authentication.
• Use OAuth 2.0 for third-party authentication (Google, GitHub, Facebook) to let users log in without sharing credentials.

For Web Applications (SSR, Traditional Web Authentication)

• Use Session & Cookies for authentication in server-rendered applications, where sessions are managed on the server and automatically sent via cookies.

For Server-to-Server Communication

• Use API Keys when backend services need to authenticate requests with external APIs without user involvement.

JWT (JSON Web Token)

JWT is a stateless authentication mechanism where authentication data is stored in a signed token rather than in a session on the server.

Composition

header.payload.signature

• Header: Specifies the signing algorithm used, such as HS256.
• Payload: Contains the actual data, for example { "username": "merrick", "exp": 123456 }.