This content originally appeared on DEV Community and was authored by Tấn Trương
Introduction
In modern application development, securing user authentication is a foundational requirement. As systems scale and threats become more sophisticated, choosing the right authentication and authorization strategy becomes critical.
Three widely adopted approaches are JWT (JSON Web Token), OAuth 2.0, and Single Sign-On (SSO). While often mentioned together, they solve different problems and are frequently used in combination.
This article provides a clear, practical comparison along with system flows and best practices.
Authentication vs Authorization
Before diving deeper:
- Authentication: Who are you?
- Authorization: What are you allowed to do?
A secure system must enforce both.
JWT (JSON Web Token)
What is JWT?
JWT is a compact, URL-safe token used to transmit claims between client and server. It is commonly used for stateless authentication.
Structure
A JWT consists of three parts:
Header.Payload.Signature
- Header: Algorithm (HS256, RS256)
- Payload: Claims (user_id, role, exp)
- Signature: Integrity verification
Flow
User → Login → Server
Server → Generate JWT → Client
Client → Attach JWT → API
API → Verify JWT → Response
Pros
- Stateless (no session storage)
- Scales well in microservices
- Fast verification
Cons
- Hard to revoke
- Token leakage risk
Best Practices
- Short-lived access tokens
- Use HTTP-only cookies
- Avoid sensitive payload data
- Implement refresh token strategy
OAuth 2.0
What is OAuth?
OAuth 2.0 is a protocol for delegated authorization. It allows applications to access user data without exposing credentials.
Roles
- Resource Owner (User)
- Client (App)
- Authorization Server
- Resource Server
Flow
User → Login + Consent → Authorization Server
Authorization Server → Access Token → Client
Client → API Request → Resource Server
Resource Server → Validate Token → Response
Grant Types
- Authorization Code (recommended)
- Client Credentials
- Implicit (deprecated)
- Password (legacy)
Best Practices
- Use Authorization Code + PKCE
- Never expose client secret
- Validate redirect URIs
- Use refresh tokens
Single Sign-On (SSO)
What is SSO?
SSO allows users to log in once and access multiple applications without re-authentication.
Flow
[ SSO Provider ]
│
┌─────────┼─────────┐
▼ ▼ ▼
App A App B App C
Technologies
- SAML (enterprise)
- OpenID Connect (modern, built on OAuth)
Pros
- Better user experience
- Centralized access control
Cons
- Single point of failure
- Higher complexity
Best Practices
- Enforce MFA
- Implement RBAC
- Monitor and audit logs
Comparison Table
| Criteria | JWT | OAuth 2.0 | SSO |
|---|---|---|---|
| Purpose | Authentication | Authorization | Central Authentication |
| State | Stateless | Token-based | Session-based |
| Use Case | APIs, microservices | Third-party access | Multi-app systems |
| Complexity | Low | Medium | High |
| Scalability | High | High | Medium |
| Revocation | Difficult | Managed by auth server | Centralized |
Real-World Architecture (Recommended)
Client
│
├── Access Token (JWT - short-lived)
├── Refresh Token (stored in DB)
│
Backend
├── Verify JWT
├── Manage session / revoke
├── Integrate OAuth providers
│
SSO Provider (optional)
Key Ideas
- Use JWT for performance
- Store refresh tokens in database (revocable)
- Route all API calls through backend
- Track device/session for security
Conclusion
There is no one-size-fits-all solution:
- Use JWT for stateless APIs
- Use OAuth 2.0 for third-party integrations
- Use SSO for unified login across systems
In practice, modern systems combine all three to achieve both security and scalability.
This content originally appeared on DEV Community and was authored by Tấn Trương
Tấn Trương | Sciencx (2026-04-23T02:35:34+00:00) Authentication Mechanisms: JWT, OAuth, and Single Sign-On (SSO). Retrieved from https://www.scien.cx/2026/04/23/authentication-mechanisms-jwt-oauth-and-single-sign-on-sso/
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