# Rate Limiter

A customizable rate-limiting and throttling middleware for Node.js applications. It allows you to limit the number of requests a client can make to your server within a specified time window.

## Features

- Flexible request limiting based on time windows.
- Easily configurable for IP-based or user-based rate limiting.
- Simple integration as middleware in Node.js apps (e.g., with Express).
- Supports both **rate limiting** and **throttling**.

## Installation

You can install the package via npm:

```bash
npm install rate-limiter
```

## Usage

### Basic Usage

The package can be used as middleware in your Node.js/Express applications to limit requests. Here's an example to allow **10 requests per second**.

```javascript
const express = require('express');
const rateLimiter = require('rate-limiter');

const app = express();

// Apply rate limiter middleware
app.use(rateLimiter({
  windowMs: 1000,   // 1 second
  maxRequests: 10   // Limit each client to 10 requests per windowMs
}));

app.get('/', (req, res) => {
  res.send('Hello, world!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});
```

### Options

The `rateLimiter` function accepts an options object to configure the behavior:

- **`windowMs`**: The time frame (in milliseconds) to allow `maxRequests`. For example, `1000` will enforce the limit per second.
- **`maxRequests`**: The maximum number of requests allowed during the `windowMs` period.

### Example: 100 Requests per 15 Minutes

```javascript
app.use(rateLimiter({
  windowMs: 15 * 60 * 1000,  // 15 minutes
  maxRequests: 100           // Limit each client to 100 requests per windowMs
}));
```

## Advanced Features

### IP-Based Limiting

By default, the middleware identifies clients by their IP address (`req.ip` in Express). This ensures that requests from each client IP are tracked separately.

### User-Based Limiting

You can also implement user-based rate limiting by passing a user identifier (such as an API key or user ID) to the rate limiter.

```javascript
app.use((req, res, next) => {
  const clientId = req.user.id; // Assuming you have user authentication
  rateLimiter({
    windowMs: 60000,   // 1 minute
    maxRequests: 30    // Limit to 30 requests per minute per user
  })(req, res, next);
});
```

## Development

If you'd like to contribute or modify the package, you can clone the repository and run it locally:

```bash
git clone https://github.com/yourusername/rate-limiter.git
cd rate-limiter
npm install
```

### Testing Locally

To run the Express example:

1. Create a file `app.js` as shown in the example above.
2. Run the server:

```bash
node app.js
```

## Contributing

Contributions are welcome! Please open issues and submit pull requests on GitHub if you'd like to improve the package.

## Issues

If you encounter any problems or have any questions, feel free to open an issue on GitHub.

## Links

- **GitHub**: [https://github.com/yourusername/rate-limiter](https://github.com/yourusername/rate-limiter)
- **NPM**: [https://www.npmjs.com/package/rate-limiter](https://www.npmjs.com/package/rate-limiter)

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