Building Secure APIs: A Developer's Guide

APIs are the backbone of modern applications, but they're also prime targets for attackers. Here's how to build APIs that are both functional and secure.

Authentication First

Never build an API without proper authentication. JWT tokens are popular, but make sure you:

- Use strong secrets

- Implement proper token expiration

- Validate tokens on every request

import jwt
from functools import wraps

def token_required(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        token = request.headers.get('Authorization')
        if not token:
            return {'message': 'Token is missing'}, 401
        try:
            data = jwt.decode(token, app.config['SECRET_KEY'])
        except:
            return {'message': 'Token is invalid'}, 401
        return f(*args, **kwargs)
    return decorated

Rate Limiting

Implement rate limiting to prevent abuse:

from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

limiter = Limiter(
    app,
    key_func=get_remote_address,
    default_limits=["200 per day", "50 per hour"]
)

@app.route('/api/data')
@limiter.limit("10 per minute")
def get_data():
    return jsonify(data)

Input Validation

Always validate and sanitize input data. Use libraries like Marshmallow for Python or Joi for Node.js.

Conclusion

Security isn't an afterthought—it should be built into your API from day one. These practices will help you create robust, secure APIs that can withstand common attacks.