How to implement rate limiting on a Node.js API?

Question

Someone is hammering my login endpoint. How do I add rate limiting that also works when I run several instances of the API?

Accepted Answer

In-memory limiters (the default `express-rate-limit` store) only count requests **per process**. With several instances you need a **shared store**, typically Redis:

```js
import { rateLimit } from 'express-rate-limit';
import { RedisStore } from 'rate-limit-redis';

app.use('/auth/login', rateLimit({
  windowMs: 15 * 60 * 1000,
  limit: 10,
  standardHeaders: 'draft-7',
  store: new RedisStore({ sendCommand: (...args) => redis.sendCommand(args) }),
}));
```

For login specifically, limit by **both IP and target account** (email). That slows credential stuffing from many IPs against one account.

Behind a proxy or load balancer, set `app.set('trust proxy', 1)` so the client IP is read correctly. Only trust `X-Forwarded-For` from your own proxy, or attackers can spoof it.

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