Authentication Explained: When to Use Basic, Bearer, OAuth2, JWT & SSO

🔐 What Is Authentication?

Authentication answers the question: Who is this user? It’s the first step before authorization (which determines what the user can do). The article breaks down five major authentication methods used in modern systems.

🧾 Authentication Methods Explained

1. Basic Authentication

• Sends username and password with every request (Base64 encoded)

• Simple but insecure unless used over HTTPS

• Rarely used in production today

2. Bearer Tokens

• Client sends a token (usually in the Authorization: Bearer <token> header)

• Token is issued after login and used for subsequent requests

• Stateless and widely adopted

3. OAuth2

• Delegated access: lets third-party apps access user data without sharing credentials

• Example: “Login with Google” or “Connect to GitHub”

• Uses access tokens and refresh tokens

• Ideal for APIs and multi-service ecosystems

4. JWT (JSON Web Tokens)

• Encodes user data (claims) into a signed token

• Used for stateless authentication and authorization

• Includes expiration, roles, and scopes

• Can be verified without a database lookup

5. SSO (Single Sign-On)

• One login grants access to multiple systems

• Common in enterprise setups (e.g., Google Workspace, Okta)

• Reduces friction and improves security

💡 Final Takeaway

Choose your authentication method based on:

• Security needs

• Scalability

• User experience

• Integration complexity

Most modern systems blend these approaches — for example, using OAuth2 to issue JWTs, or combining SSO with role-based access control.