Rate Limiter Algorithms

A rate limiting library that provides various algorithms and works in any Javascript environment.\
You can find more information about algorithms in this article.

!NPM Version
!NPM Downloads
![LICENSE
](LICENSE)

Example with Node.js

``ts
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) => {
// any unique key like ip address or user id
const uniqueKey = req.socket.remoteAddress;

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

// 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

$3

Default in-memory option. Example:

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

const limiter = new RateLimiter({
algorithm: "token-bucket",
limit: 5,
windowMs: 5000,
store: new MemoryStore(), // defaults to this value if unspecified
});
`

$3

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

`ts
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:", // defaults to this value if unspecified
rawCall: (...args: string[]) => client.sendCommand(args),
}),,
});
`

Raw command list:

| Library | Function |
| --------------------------------------------------- | ----------------------------------------------------------------------- |
| node-redis | (...args: string[]) => client.sendCommand(args) |
| ioredis | (command: string, ...args: string[]) => client.call(command, ...args)` |

License

All code and documentation are (c) 2024-Present Eugene Shumilin and released under the MIT License