Rate-limiter-algorithms NPM

Rate Limiter Algorithms

Library that provides different algorithms to perform rate limiting.

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Example with Node.js

import { createServer } from "node:http";
import { RateLimiter } from "rate-limiter-algorithms";

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
});

const server = createServer(async (req, res) => {
    const ip = req.socket.remoteAddress || "any unique key";

    try {
        const { isAllowed, clientData } = await limiter.consume(ip);

        // set rate limiting headers
        const headers = limiter.getHeaders(clientData);
        for (const header of headers) {
            res.setHeader(header[0], header[1]);
        }

        if (!isAllowed) {
            res.writeHead(429, "Too many requests");
            res.end("Failure");
            return;
        }
        res.end("Success");
    } catch (error) {
        console.error("Error in rate limiting:", error);
    }
});

server.listen(3000, "127.0.0.1", () => {
    console.log("Listening on 127.0.0.1:3000");
});

Config

Option	Type	Explanation
`algorithm`	`string`	Values: `token-bucket`, `fixed-window-counter`, `sliding-window-logs`, `sliding-window-counter`
`windowMs`	`number`	Duration of time in milliseconds when algorithm updates its counter.
`limit`	`number`	Maximum amount of points that client can consume
`store`	`Store`	Store which contains clients data based on chosen algorithm. Defaults to Memory Store

Date Stores

Memory Store

Default in-memory option. Example:

import { RateLimiter, MemoryStore } from "rate-limiter-algorithms";

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
    store: new MemoryStore(),
});

Redis Store

Uses rawCall function to send raw commands to Redis. Example for node-redis :

import { RateLimiter, RedisStore } from "rate-limiter-algorithms";
import { createClient } from "redis";

const client = createClient();
client.connect();

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
    store: new RedisStore({
        prefix: "rla:", // it's default prefix
        rawCall: (...args: string[]) => client.sendCommand(args),
    }),,
});

Raw command list: