Rate Limiter

Simple rate limiting with token bucket and sliding window algorithms.

Installation

npm install rate-limiter

Quick Start

import { createLimiter, KeyedRateLimiter } from 'rate-limiter';

// Simple limiter
const limiter = createLimiter({ limit: 100, windowMs: 60000 });

if (limiter.consume()) {
  // Process request
} else {
  // Rate limited
}

// Per-user limiting
const userLimiter = new KeyedRateLimiter({ limit: 10, windowMs: 60000 });
userLimiter.consume(userId);

Algorithms

Token Bucket

Allows bursting up to capacity, then refills over time.

const limiter = new TokenBucket({
  capacity: 10,         // Maximum tokens
  refillRate: 1,        // Tokens added per interval
  refillInterval: 1000  // Refill interval (ms)
});

Fixed Window

Limits requests per fixed time window.

const limiter = new FixedWindow({
  limit: 100,       // Requests per window
  windowMs: 60000   // Window duration (ms)
});

Sliding Window

More accurate rate limiting using sliding windows.

const limiter = new SlidingWindow({
  limit: 100,
  windowMs: 60000
});

API

Common Methods

limiter.consume()   // Try to consume, returns boolean
limiter.check()     // Check without consuming
limiter.remaining() // Get remaining requests
limiter.reset()     // Reset the limiter

KeyedRateLimiter

For per-user/IP rate limiting:

const limiter = new KeyedRateLimiter({
  limit: 10,
  windowMs: 60000,
  algorithm: 'sliding'  // 'sliding', 'fixed', 'token'
});

limiter.consume('user123')
limiter.check('user123')
limiter.remaining('user123')
limiter.reset('user123')
limiter.clear()  // Clear all

createLimiter(options)

Factory function:

createLimiter({ algorithm: 'sliding', limit: 100 })
createLimiter({ algorithm: 'token', capacity: 10 })
createLimiter({ algorithm: 'fixed', limit: 100 })

License

MIT