Best Practices for API Security

Why Secure APIs?

APIs expose your application’s functionality to external consumers. A breach can lead to data theft, service disruption, and loss of trust. Implementing a layered security approach protects both your data and your users.

Authentication & Authorization

Use industry‑standard protocols like OAuth 2.0 and OpenID Connect. Prefer short‑lived JWTs with proper scopes.

// Example: Verify a JWT in Node.js
const jwt = require('jsonwebtoken');
function verifyToken(req, res, next) {
  const token = req.headers['authorization']?.split(' ')[1];
  if (!token) return res.sendStatus(401);
  jwt.verify(token, process.env.JWT_SECRET, (err, decoded) => {
    if (err) return res.sendStatus(403);
    req.user = decoded;
    next();
  });
}

Rate Limiting & Throttling

Prevent abuse by limiting the number of requests per IP or per user.

// Example: Express-rate-limit
const rateLimit = require('express-rate-limit');
app.use(rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 100,
  message: 'Too many requests, try again later.'
}));

Input Validation & Sanitization

Never trust client data. Validate schemas and sanitize strings to avoid injection attacks.

// Example: Joi schema validation
const Joi = require('joi');
const schema = Joi.object({
  email: Joi.string().email().required(),
  age: Joi.number().integer().min(0)
});
app.post('/users', (req, res) => {
  const { error } = schema.validate(req.body);
  if (error) return res.status(400).send(error.details[0].message);
  // continue processing...
});

Logging & Monitoring

Log authentication failures, unusual patterns, and audit trails. Use tools like ELK or Azure Monitor.

Encryption at Rest & in Transit

Enforce HTTPS everywhere (HSTS). Encrypt sensitive data at rest using AES‑256.

Security Testing

Run regular scans with OWASP ZAP, post‑man security tests, and include static analysis in CI pipelines.