Main Differences: OAuth2, JWT, OAuth2 + JWT
What each term actually is
OAuth2
OAuth2 is an authorization framework, not a token format. It defines how clients get permission, how tokens are issued, and how protected resources are accessed.
Example use cases:
- Login with Google
- Third-party apps accessing user data
JWT (JSON Web Token)
JWT is a token format. It is a compact, signed JSON object used to securely transmit claims.
- Can be used with OAuth2
- Can be used without OAuth2
- Commonly used for API authentication
OAuth2 + JWT
This means OAuth2 is used as the authorization framework and JWT is used as the access token format. This is very common in modern APIs and microservices.
Comparison Table
| Feature | OAuth2 | JWT | OAuth2 + JWT |
|---|---|---|---|
| What it is | Authorization framework | Token format | OAuth2 using JWT tokens |
| Purpose | Access delegation | Secure data exchange | Auth + stateless access |
| Defines flows | Yes | No | Yes |
| Token type | Opaque or JWT | JWT only | JWT |
| Stateless | Usually No | Yes | Yes |
| Can work alone | No | Yes | No |
| Common use | Google login | Simple API auth | Modern APIs |
Authentication Flow Examples
OAuth2
Client → Auth Server → Access Token → Resource Server
JWT (standalone)
User → Login → JWT → API
OAuth2 + JWT
User → OAuth2 Login → JWT Access Token → API
Security Perspective
OAuth2
- Secure
- Complex
- Often requires token storage
JWT
- Stateless and fast
- No DB lookup required
- Hard to revoke
- Risk if token is leaked
OAuth2 + JWT
- Scalable
- Stateless
- Needs careful expiry and rotation
FastAPI Context
- FastAPI commonly uses
OAuth2PasswordBearer - JWT is used as the access token
- Token validation uses signature and expiration
OAuth2: A framework that defines how access tokens are issued and used.
JWT: A compact, stateless token format for securely transmitting claims.
OAuth2 + JWT: OAuth2 using JWT as the access token for modern APIs.
Summary
- JWT can be an access token, but OAuth2 is responsible for issuing and managing access tokens.