arcjet

arcjet

Arcjet helps developers protect their apps in just a few lines of code. Implement rate limiting, bot protection, email verification, and defense against common attacks.

This is the Arcjet TypeScript and JavaScript SDK core.

Getting started

Visit docs.arcjet.com to get started.

Generally, you'll want to use the Arcjet SDK for your specific framework, such as @arcjet/next for Next.js. However, this package can be used to interact with Arcjet if your framework does not have an integration.

Installation

npm install -S arcjet

Rate limit + bot detection example

The example below applies a token bucket rate limit rule to a route where we identify the user based on their ID e.g. if they are logged in. The bucket is configured with a maximum capacity of 10 tokens and refills by 5 tokens every 10 seconds. Each request consumes 5 tokens.

Bot detection is also enabled to block requests from known bots.

import http from "http";
import arcjet, { createRemoteClient, tokenBucket, detectBot } from "arcjet";
import { baseUrl } from "@arcjet/env";
import { createConnectTransport } from "@connectrpc/connect-node";

const aj = arcjet({
  // Get your site key from https://app.arcjet.com
  // and set it as an environment variable rather than hard coding.
  // See: https://www.npmjs.com/package/dotenv
  key: process.env.ARCJET_KEY,
  characteristics: ["userId"], // track requests by a custom user ID
  rules: [
    // Create a token bucket rate limit. Other algorithms are supported.
    tokenBucket({
      mode: "LIVE", // will block requests. Use "DRY_RUN" to log only
      refillRate: 5, // refill 5 tokens per interval
      interval: 10, // refill every 10 seconds
      capacity: 10, // bucket maximum capacity of 10 tokens
    }),
    detectBot({
      mode: "LIVE", // will block requests. Use "DRY_RUN" to log only
      // configured with a list of bots to allow from
      // https://arcjet.com/bot-list
      allow: [], // "allow none" will block all detected bots
    }),
  ],
  client: createRemoteClient({
    transport: createConnectTransport({
      baseUrl: baseUrl(process.env),
      httpVersion: "2",
    }),
  }),
});

const server = http.createServer(async function (
  req: http.IncomingMessage,
  res: http.ServerResponse,
) {
  // Any sort of additional context that might want to be included for the
  // execution of `protect()`. This is mostly only useful for writing adapters.
  const ctx = {};

  // Construct an object with Arcjet request details
  const path = new URL(req.url || "", `http://${req.headers.host}`);
  const details = {
    ip: req.socket.remoteAddress,
    method: req.method,
    host: req.headers.host,
    path: path.pathname,
  };

  const decision = await aj.protect(ctx, details, { requested: 5 }); // Deduct 5 tokens from the bucket
  console.log(decision);

  if (decision.isDenied()) {
    res.writeHead(403, { "Content-Type": "application/json" });
    res.end(JSON.stringify({ error: "Forbidden" }));
  } else {
    res.writeHead(200, { "Content-Type": "application/json" });
    res.end(JSON.stringify({ data: "Hello World!" }));
  }
});

server.listen(8000);

API

Reference documentation is available at docs.arcjet.com.

License

Licensed under the Apache License, Version 2.0.

Changelog

1.0.0-beta.2 (2025-02-04)

🚀 New Features

• env: Support MODE environment variable for isDevelopment detection (#3012) (f3a45a7)
• Implement Astro integration (#2992) (a48eea8), closes #1075
• nestjs: Allow NestJS v11 as peerDependency (#3042) (4a75963), closes #2921
• redact: Pre-compile WebAssembly on module load (#3037) (c12bec5)

🪲 Bug Fixes

• analyze: Always lowercase headers and iterate in insertion order (#2865) (a9af1e4)
• arcjet: Ensure Characteristics are readonly type on protect signup options (#3013) (1f16a99)
• protocol: Double timeout when email rule configured (#2934) (23f9a9e), closes #1697

🧹 Miscellaneous Chores

• ci: Add dependabot for Astro example (#3068) (d4d8f82)
• ci: Avoid upgrading Tailwind where it breaks things (#3081) (5c25abe)
• ci: Restrict tailwind-merge where tailwind restricted (#3089) (a3437a5)
• docs: Add a link to the Redact reference page (#3038) (6095b6a)
• Refresh root & Next.js READMEs (#3066) (57a38d7)
• rollup-config: Consolidate wasmToModule plugin (#3039) (c3b8e36)