Bot protection quick start
Arcjet bot detection allows you to manage traffic by automated clients and bots.
What is Arcjet?
Arcjet helps developers protect their apps in just a few lines of code. Bot detection. Rate limiting. Email validation. Attack protection. Data redaction. A developer-first approach to security.Quick start
This guide will show you how to protect your entire
1. Install Arcjet
In your project root, run the following command to install the SDK:
bun add @arcjet/bundeno add npm:@arcjet/denonpm i @arcjet/nextpnpm add @arcjet/nextyarn add @arcjet/nextnpm i @arcjet/nodepnpm add @arcjet/nodeyarn add @arcjet/nodenpm i @arcjet/sveltekitpnpm add @arcjet/sveltekityarn add @arcjet/sveltekit2. Set your key
Create a free Arcjet account then follow the instructions to add a site and get a key.
Add your key to a .env.local file in your project root.
# NODE_ENV is not set automatically, so tell Arcjet we're in dev# You can leave this unset in prodARCJET_ENV=development# Get your site key from https://app.arcjet.comARCJET_KEY=ajkey_yourkeyAdd your key to a .env file in your project root.
# NODE_ENV is not set automatically, so tell Arcjet we're in dev# You can leave this unset in prodARCJET_ENV=development# Get your site key from https://app.arcjet.comARCJET_KEY=ajkey_yourkeyAdd your key to a .env.local file in your project root.
ARCJET_KEY=ajkey_yourkeyAdd your key to a .env.local file in your project root.
# NODE_ENV is not set automatically, so tell Arcjet we're in dev# You can leave this unset in prodARCJET_ENV=development# Get your site key from https://app.arcjet.comARCJET_KEY=ajkey_yourkeyAdd your key to a .env file in your project root.
ARCJET_KEY=ajkey_yourkey3. Add bot protection
The example below will return a 403 Forbidden response for all requests from clients we are sure are automated.
import arcjet, { detectBot } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
if (decision.isDenied()) { return new Response("Forbidden", { status: 403 }); }
return new Response("Hello world"); }),};import arcjet, { detectBot } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
if (decision.isDenied()) { return new Response("Forbidden", { status: 403 }); }
return new Response("Hello world"); }),};The example below will return a 403 Forbidden response for all requests from clients we are sure are automated.
import "jsr:@std/dotenv/load";
import arcjet, { detectBot } from "@arcjet/deno";
const aj = arcjet({ key: Deno.env.get("ARCJET_KEY")!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
Deno.serve( { port: 3000 }, aj.handler(async (req) => { const decision = await aj.protect(req);
if (decision.isDenied()) { return new Response("Forbidden", { status: 403 }); }
return new Response("Hello world"); }),);The example below will return a 403 Forbidden response for all requests from clients we are sure are automated.
import arcjet, { detectBot } from "@arcjet/node";import http from "node:http";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
const server = http.createServer(async function (req, res) { const decision = await aj.protect(req); console.log("Arcjet decision", 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({ message: "Hello world" })); }});
server.listen(8000);import arcjet, { detectBot } from "@arcjet/node";import http from "node:http";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
const server = http.createServer(async function ( req: http.IncomingMessage, res: http.ServerResponse,) { const decision = await aj.protect(req); console.log("Arcjet decision", 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({ message: "Hello world" })); }});
server.listen(8000);Create a new API route at /src/routes/api/arcjet/+server.js:
import { env } from "$env/dynamic/private";import arcjet, { detectBot } from "@arcjet/sveltekit";import { error } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export async function handle({ event, resolve }) { const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "Forbidden"); }
return resolve(event);}Create a new API route at /src/routes/api/arcjet/+server.ts:
import { env } from "$env/dynamic/private";import arcjet, { detectBot } from "@arcjet/sveltekit";import { error, type RequestEvent } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export async function handle({ event, resolve,}: { event: RequestEvent; resolve: (event: RequestEvent) => Response | Promise<Response>;}): Promise<Response> { const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "Forbidden"); }
return resolve(event);}For this quick start we will enable Arcjet Bot Protection across your entire Next.js application. Next.js middleware runs before every request, allowing Arcjet to protect your entire application before your code runs.
The basic option exports the middleware directly whereas the advanced option allows you to customize the response based on the Arcjet decision.
Create a file called middleware.ts in your project root (at the same level as
pages or app or inside src).
import arcjet, { createMiddleware, detectBot } from "@arcjet/next";export const config = { // matcher tells Next.js which routes to run the middleware on. // This runs the middleware on all routes except for static assets. matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],};const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});// Pass any existing middleware with the optional existingMiddleware propexport default createMiddleware(aj);Create a file called middleware.js in your project root (at the same level as
pages or app or inside src):
import arcjet, { createMiddleware, detectBot } from "@arcjet/next";export const config = { // matcher tells Next.js which routes to run the middleware on. // This runs the middleware on all routes except for static assets. matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],};const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});// Pass any existing middleware with the optional existingMiddleware propexport default createMiddleware(aj);Create a file called middleware.ts in your project root (at the same level as
pages or app or inside src).
import arcjet, { detectBot } from "@arcjet/next";import { NextRequest, NextResponse } from "next/server";
export const config = { // matcher tells Next.js which routes to run the middleware on. // This runs the middleware on all routes except for static assets. matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],};const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export default async function middleware(request: NextRequest) { const decision = await aj.protect(request);
if ( // If this deny comes from a bot rule then block the request. You can // customize this logic to fit your needs e.g. changing the status code. decision.isDenied() && decision.reason.isBot() ) { return NextResponse.json({ error: "Unauthorized" }, { status: 403 }); } else { return NextResponse.next(); }}Create a file called middleware.js in your project root (at the same level as
pages or app or inside src):
import arcjet, { detectBot } from "@arcjet/next";import { NextResponse } from "next/server";
export const config = { // matcher tells Next.js which routes to run the middleware on. // This runs the middleware on all routes except for static assets. matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],};const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ detectBot({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only // Block all bots except the following allow: [ "CATEGORY:SEARCH_ENGINE", // Google, Bing, etc // Uncomment to allow these other common bot categories // See the full list at https://arcjet.com/bot-list //"CATEGORY:MONITOR", // Uptime monitoring services //"CATEGORY:PREVIEW", // Link previews e.g. Slack, Discord ], }), ],});
export default async function middleware(request) { const decision = await aj.protect(request);
if ( // If this deny comes from a bot rule then block the request. You can // customize this logic to fit your needs e.g. checking the IP address type // or changing the status code. decision.isDenied() && decision.reason.isBot() ) { return NextResponse.json({ error: "Unauthorized" }, { status: 403 }); } else { return NextResponse.next(); }}4. Start server
Start your Bun server:
bun run --hot index.tsbun run --hot index.jsMake a curl request from your terminal. You should see a 403 Forbidden
response because curl is considered an automated client by default.
# Will show the response status, which should be 403 forbiddencurl -i http://localhost:3000The requests will also show up in the Arcjet dashboard.
4. Start server
Start your Deno server:
deno run --watch index.tsMake a curl request from your terminal. You should see a 403 Forbidden
response because curl is considered an automated client by default.
curl http://localhost:3000The requests will also show up in the Arcjet dashboard.
4. Start app
Start your Next.js app:
npm run devpnpm run devyarn run devMake a curl request from your terminal to your application. You should see a
403 Forbidden response because curl is considered an automated client by
default. See the reference guide to learn about
configuring this.
# Will show the response headers, which should be 403 forbiddencurl -i http://localhost:3000The requests will also show up in the Arcjet dashboard.
4. Start server
Start your Node.js server:
npx tsx --env-file .env.local index.tsnode --env-file .env.local index.jsMake a curl request from your terminal to your application. You should see a
403 Forbidden response because curl is considered an automated client by
default. See the reference guide to learn about
configuring this.
# Will show the response headers, which should be 403 forbiddencurl -i http://localhost:8000The requests will also show up in the Arcjet dashboard.
4. Start app
Start your SvelteKit app:
npm run devpnpm run devyarn run devMake a curl request from your terminal to your application. You should see a
403 Forbidden response because curl is considered an automated client by
default. See the reference guide to learn about
configuring this.
# Will show the response status, which should be 403 forbiddencurl -i http://localhost:5173The requests will also show up in the Arcjet dashboard.
5. Choose bots to allow or deny
Arcjet maintains a list of known bots so you can choose to either only allow specific bots or only deny specific bots.
Check out our full list of bots.
FAQs
Do I need to run any infrastructure e.g. Redis?
No, Arcjet handles all the infrastructure for you so you don't need to worry about deploying global Redis clusters, designing data structures to track rate limits, or keeping security detection rules up to date.
What is the performance overhead?
Arcjet SDK tries to do as much as possible asynchronously and locally to minimize latency for each request. Where decisions can be made locally or previous decisions are cached in-memory, latency is usually <1ms.
When a call to the Arcjet API is required, such as when tracking a rate limit in a serverless environment, there is some additional latency before a decision is made. The Arcjet API has been designed for high performance and low latency, and is deployed to multiple regions around the world. The SDK will automatically use the closest region which means the total overhead is typically no more than 20-30ms, often significantly less.
What happens if Arcjet is unavailable?
Where a decision has been cached locally e.g. blocking a client, Arcjet will continue to function even if the service is unavailable.
If a call to the Arcjet API is needed and there is a network problem or Arcjet is unavailable, the default behavior is to fail open and allow the request. You have control over how to handle errors, including choosing to fail close if you prefer. See the reference docs for details.
How does Arcjet protect me against DDoS attacks?
Network layer attacks tend to be generic and high volume, so these are best handled by your hosting platform. Most cloud providers include network DDoS protection by default.
Arcjet sits closer to your application so it can understand the context. This is important because some types of traffic may not look like a DDoS attack, but can still have the same effect. For example, a customer making too many API requests and affecting other customers, or large numbers of signups from disposable email addresses.
Network-level DDoS protection tools find it difficult to protect against this type of traffic because they don't understand the structure of your application. Arcjet can help you to identify and block this traffic by integrating with your codebase and understanding the context of the request e.g. the customer ID or sensitivity of the API route.
Volumetric network attacks are best handled by your hosting provider. Application level attacks need to be handled by the application. That's where Arcjet helps.
What next?
Arcjet can be used with specific rules on individual routes or as general protection on your entire application. You can customize bot protection, rate limiting for your API and minimize fraudulent registrations with the signup form protection.
Get help
Need help with anything? Email support@arcjet.com to get support from our engineering team.