Bot protection for Next.js

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. Implement rate limiting, bot protection, email verification & defend against common attacks.

Quick start

This guide will show you how to protect your entire Next.js application from bots and automated clients.

1. Install Arcjet

In your project root, run the following command to install the SDK:

npm i @arcjet/next

pnpm add @arcjet/next

yarn add @arcjet/next

2. Set your key

Create a free Arcjet account then follow the instructions to add a site and get a key. Add it to a .env.local file in your Next.js project root:

ARCJET_KEY=ajkey_yourkey

3. Add bot protection middleware

If you wish to enable Arcjet Bot Protection across your entire Next.js application, you can install the SDK as middleware. Next.js middleware runs before every request, allowing Arcjet to protect your entire application before your code runs.

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: ["AUTOMATED"], // blocks all automated clients
    }),
  ],
});
// Pass any existing middleware with the optional existingMiddleware prop
export 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: ["AUTOMATED"], // blocks all automated clients
    }),
  ],
});
// Pass any existing middleware with the optional existingMiddleware prop
export default createMiddleware(aj);

4. Start app

Make 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 for how to configure this.

# Will show just the response headers, which should be 403 forbidden
curl -I http://localhost:3000

The requests will also show up in the Arcjet dashboard.

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?

Bot protection reference Full details about bot protection.

Get help

Need help with anything? Email us or join our Discord to get support from our engineering team.