APIs are the most common attack vector in modern application security. The OWASP API Security Top 10 documents the most critical API vulnerabilities, and the list grows longer each year as APIs proliferate. Securing your APIs is not optional it is a fundamental requirement for any business that handles customer data.
The OWASP API Security Top 10
The Open Web Application Security Project (OWASP) maintains a list of the most critical API security risks. Understanding these risks is the foundation of API security.
| Risk | Description | Prevention |
|---|---|---|
| Broken Object Level Authorization | API returns data for any object ID | Validate user owns the requested object |
| Broken Authentication | Weak or missing authentication | Implement OAuth 2.0 + JWT properly |
| Excessive Data Exposure | API returns more data than needed | Return only required fields |
| Lack of Rate Limiting | No limits on API request volume | Implement rate limiting per user/IP |
| Broken Function Level Authorization | Users can access admin functions | Separate admin and user API surfaces |
| Mass Assignment | API accepts all input fields | Whitelist allowed input fields explicitly |
| Security Misconfiguration | Default settings left in place | Security-focused configuration review |
| Injection | SQL/NoSQL injection via API inputs | Parameterized queries, input validation |
Authentication and Authorization
OAuth 2.0 and JWT
OAuth 2.0 is the industry standard for API authorization. JSON Web Tokens (JWT) are the standard format for access tokens. Implement short-lived access tokens (15-60 minutes) with refresh token rotation. Never store tokens in localStorage use httpOnly cookies for web applications.