API Key vs OAuth vs JWT: Authentication Comparison

Understanding the differences between API keys, OAuth 2.0, and JWT is essential for building secure applications. Each method serves different use cases and comes with its own trade-offs.

API Keys

API keys are simple static strings that identify the client application. They are best suited for server-to-server communication where you need to identify which service is making requests.

• Use cases: Public APIs, server-to-server auth, identifying applications
• Pros: Simple to implement, stateless, low overhead
• Cons: No expiration, limited permissions, can be leaked easily

OAuth 2.0

OAuth 2.0 is an authorization framework that enables applications to obtain limited access to user accounts. It delegates user authentication to the service hosting the account.

• Use cases: User login, third-party app access, social login
• Pros: User consent, scoped permissions, token expiration
• Cons: Complex implementation, requires redirect flows

JWT (JSON Web Tokens)

JWTs are self-contained tokens that carry claims about the user. They can be verified without querying a database, making them excellent for distributed systems.

• Use cases: Stateless authentication, microservices, API authorization
• Pros: Stateless, can contain user data, cryptographically signed
• Cons: Cannot be revoked before expiration, larger than API keys

When to Use What

Use API keys for simple service identification. Use OAuth for user authentication with consent. Use JWTs for stateless API authorization in microservices architectures.