JWT Decoding and Validation: Essential Practices for Secure OAuth 2.0 Implementations
I’ve debugged hundreds of JWT validation bugs in production - most stem from skipping one critical step. JSON Web Tokens are the backbone of modern OAuth 2.0 auth, and getting validation right is non-negotiable. Visual Overview: sequenceDiagram participant User participant App as Client App participant AuthServer as Authorization Server participant Resource as Resource Server User->>App: 1. Click Login App->>AuthServer: 2. Authorization Request AuthServer->>User: 3. Login Page User->>AuthServer: 4. Authenticate AuthServer->>App: 5. Authorization Code App->>AuthServer: 6. Exchange Code for Token AuthServer->>App: 7. Access Token + Refresh Token App->>Resource: 8. API Request with Token Resource->>App: 9. Protected Resource Why This Matters According to OWASP’s API Security Top 10, broken authentication consistently ranks in the top 3 vulnerabilities. JWT validation is your first line of defense. Skip signature verification? You’re accepting forged tokens. Ignore expiration? Attackers replay stolen tokens indefinitely. ...