limitngin

A lightweight, zero-dependency ESM-only rate limiter middleware for Express.
Implements a simple and efficient fixed-interval request counter using an in-memory store.

The package exports a default ESM function that creates a LimitNgin instance and returns a ready-to-use Express middleware.

Installation

npm install limitngin

Quick Start (Express — ESM Only)

import express from "express";
import limitNgin from "limitngin";

const app = express();

app.use(
  limitNgin({
    intervalInSec: 60,
    allowedNoOfRequests: 100
  })
);

app.get("/", (req, res) => {
  res.json({ message: "OK" });
});

app.listen(3000, () => console.log("server running"));

Note:
This package is pure ESM.
Use import — require() is not supported.

API

Default Export

limitNgin(config?: LimitNginConfig)

Returns an Express middleware function that performs rate limiting.

Configuration

export type LimitNginConfig = {
  intervalInSec: number;
  allowedNoOfRequests: number;
};

Defaults

intervalInSec: 60
allowedNoOfRequests: 100

How It Works

The middleware maintains a simple in-memory store:

{
  "<ip>": {
    req_count: number;
    created_at: number;
  }
}

Automatic Cleanup

Runs every:

max(intervalInSec, 60) seconds

Example Blocked Response

{
  "message": "too many request"
}

Upcoming Enhancements

• Retry-After header
• Better cleanup
• Pluggable storage adapters
• Framework-agnostic version

License

MIT