Secure API Design Principles

Building an API is easy. Building a secure API requires discipline.

1. Always Use HTTPS

There is no excuse for HTTP in production. Use TLS/SSL to encrypt data in transit.

2. Rate Limiting

Prevent abuse (and huge server bills) by limiting how many requests a user can make.

// Example: limit each IP to 100 requests per windowMs
const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100
});

3. Input Validation

Never trust the client. If your API expects an email, check that it is an email. If it expects a number, ensure it's not a SQL injection string.

Libraries like Zod or Joi are excellent for this.

4. Proper Authentication

Don't roll your own crypto. Use standards like OAuth2 or JWT (JSON Web Tokens). Ensure tokens have expiration times.

Security is not a feature; it's a foundation.