How to: ![✔] 6.2. Limit concurrent requests using a middleware
**TL;DR:** DOS attacks are very popular and relatively easy to conduct. Implement rate limiting using an external service such as cloud load balancers, cloud firewalls, nginx, [rate-limiter-flexible](https://www.npmjs.com/package/rate-limiter-flexible) package, or (for smaller and less critical apps) a rate-limiting middleware (e.g. [express-rate-limit](https://www.npmjs.com/package/express-rate-limit))

**Otherwise:** An application could be subject to an attack resulting in a denial of service where real users receive a degraded or unavailable service.

🔗 [**Read More: Implement rate limiting**](./sections/security/limitrequests.md)