Shield reference
Arcjet Shield protects your application against common attacks, including the OWASP Top 10.
Configuration
Shield is configured by specifying which mode you want it to run in.
The configuration definition is:
type ShieldOptions = { mode?: "LIVE" | "DRY_RUN";};The arcjet client is configured with one or more shield rules which take
one or many ShieldOptions.
Loader vs action
Remix does not support middleware, instead they recommend calling functions directly inside the loader. Loaders execute before the page is loaded.
All our examples use this pattern, but you can also execute Arcjet in an
action. This would be appropriate
to protect a form submission or other non-GET request.
For example, you might want to run Shield on every GET page load, but use
Shield and email validation in an action handling a form POST.
Action
This example shows how to run Arcjet in a Remix action:
import arcjet, { shield } from "@arcjet/remix";import type { ActionFunctionArgs } from "@remix-run/node";import { redirect } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export async function action(args: ActionFunctionArgs) { const decision = await aj.protect(args);
if (decision.isDenied()) { // This redirects to a generic error page (which you should create), but you // could also throw an error return redirect(`/error`); }
// ... // Process the action here // ...
return null;}import arcjet, { shield } from "@arcjet/remix";import { redirect } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export async function action(args) { const decision = await aj.protect(args);
if (decision.isDenied()) { // This redirects to a generic error page (which you should create), but you // could also throw an error return redirect(`/error`); }
// ... // Process the action here // ...
return null;}Guards and routes
Arcjet can be integrated into NestJS in several places using NestJS guards or directly within the route controller:
- Global guard: Applies Arcjet rules on every request, but does not allow you to configure rules per route.
- Per route guard: Allows you to configure rules per route, but requires you to add the guard to every route and has limited flexibility.
- Within route: Requires some code duplication, but allows maximum flexibility because you can customize the rules and response.
For Shield we recommend including it on the root module so it can analyze all requests.
Global guard
A global guard can be configured in src/app.module.ts.
import { ArcjetModule, shield } from "@arcjet/nest";import { Module } from "@nestjs/common";import { ConfigModule } from "@nestjs/config";//import { AppController } from './app.controller.js';//import { AppService } from './app.service.js';
@Module({ imports: [ ConfigModule.forRoot({ isGlobal: true, envFilePath: ".env.local", }), ArcjetModule.forRoot({ isGlobal: true, key: process.env.ARCJET_KEY!, rules: [ // Applies to every request shield({ mode: "LIVE", }), ], }), // ... other modules ], //controllers: [AppController], //providers: [AppService],})export class AppModule {}This can then be added to the controller for all the routes you wish to protect with Arcjet.
import { ArcjetGuard } from "@arcjet/nest";import { Controller, Get, Injectable, UseGuards } from "@nestjs/common";
// This would normally go in your controller file e.g.// src/page/page.controller.ts@Controller("page")// Uses the ArcjetGuard to protect the controller with the default rules defined// in app.module.ts. Using a guard makes it easy to apply Arcjet rules, but you// don't get access to the decision.@UseGuards(ArcjetGuard)export class PageController { constructor(private readonly pageService: PageService) {}
@Get() index() { return this.pageService.message(); }}
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageService { message(): { message: string } { return { message: "Hello world", }; }}Per route guard
A per route guard can be configured in the controller for each route you wish to
protect with specific Arcjet rules. The client created in src/app.module.ts
is automatically passed to the guard.
The rules will be applied and a generic error returned if the result is DENY.
import { WithArcjetRules, shield } from "@arcjet/nest";import { Injectable, Get } from "@nestjs/common";
// This would normally go in your controller file e.g.// src/page/page.controller.ts// Attaches the ArcjetGuard to the controller to protect it with the specified// rules extended from the global rules defined in app.module.ts.@WithArcjetRules([ shield({ mode: "LIVE", }),])export class PageController { constructor(private readonly pageService: PageService) {}
@Get() index() { return this.pageService.message(); }}
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageService { message(): { message: string } { return { message: "Hello world", }; }}Within route
Call Arcjet from within the route controller to have maximum flexibility.
import { ARCJET, type ArcjetNest, shield } from "@arcjet/nest";import { Controller, Get, HttpException, HttpStatus, Inject, Injectable, Req,} from "@nestjs/common";import type { Request } from "express";
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageAdvancedService { message(): { message: string } { return { message: "Hello world", }; }}
// This would normally go in your controller file e.g.// src/page/page.controller.ts@Controller("page")// Sets up the Arcjet protection without using a guard so we can access the// decision and use it in the controller.export class PageAdvancedController { constructor( private readonly pageService: PageAdvancedService, @Inject(ARCJET) private readonly arcjet: ArcjetNest, ) {}
@Get() async index(@Req() req: Request) { const decision = await this.arcjet .withRule( shield({ mode: "LIVE", }), ) .protect(req);
if (decision.isDenied()) { if (decision.reason.isShield()) { throw new HttpException("No attacks allowed", HttpStatus.FORBIDDEN); } else { throw new HttpException("Forbidden", HttpStatus.FORBIDDEN); } }
return this.pageService.message(); }}Per route vs middleware
Shield can be configured in two ways:
- Per API route: The rule is defined in the API route itself. This allows you to configure the rule alongside the code it is protecting which is useful if you want to use the decision to add context to your own code. However, it means rules are not located in a single place.
- Middleware: The rule is defined in the middleware. This allows you to configure rules in a single place or apply them globally to all routes, but it means the rules are not located alongside the code they are protecting.
Per route
import arcjet, { shield } from "@arcjet/next";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export default async function handler(req, res) { const decision = await aj.protect(req);
if (decision.isDenied() && decision.reason.isShield()) { return res.status(403).json({ error: "You are suspicious!" }); // Returning the reason is useful for debugging, but don't return it to the // client in production // .json({ error: "You are suspicious!", reason: decision.reason }); }
res.status(200).json({ name: "Hello world" });}import arcjet, { shield } from "@arcjet/next";import type { NextApiRequest, NextApiResponse } from "next";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export default async function handler( req: NextApiRequest, res: NextApiResponse,) { const decision = await aj.protect(req);
if (decision.isDenied() && decision.reason.isShield()) { return res.status(403).json({ error: "You are suspicious!" }); // Returning the reason is useful for debugging, but don't return it to the // client in production // .json({ error: "You are suspicious!", reason: decision.reason }); }
res.status(200).json({ name: "Hello world" });}import arcjet, { shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(req: Request) { const decision = await aj.protect(req);
if (decision.isDenied() && decision.reason.isShield()) { return NextResponse.json( { error: "You are suspicious!", // Useful for debugging, but don't return it to the client in // production //reason: decision.reason, }, { status: 403 }, ); }
return NextResponse.json({ message: "Hello world", });}import arcjet, { shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(req) { const decision = await aj.protect(req);
if (decision.isDenied() && decision.reason.isShield()) { return NextResponse.json( { error: "You are suspicious!", // Useful for debugging, but don't return it to the client in // production //reason: decision.reason, }, { status: 403 }, ); }
return NextResponse.json({ message: "Hello world", });}Middleware
This will run on every request to your Next.js app, except for static assets
(configured in the matcher - see the Next.js
docs
for details).
Create a file called middleware.ts in your project root (at the same level as
pages or app or inside src):
import arcjet, { createMiddleware, shield } 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: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});// 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, shield } 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: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});// Pass any existing middleware with the optional existingMiddleware propexport default createMiddleware(aj);Avoiding double protection with middleware
If you use Arcjet in middleware and individual routes, you need to be careful that Arcjet is not running multiple times per request. This can be avoided by excluding the API route from the middleware matcher.
For example, if you already have a shield rule defined in the API route
at /api/hello, you can exclude it from the middleware by specifying a matcher
in /middleware.ts:
import arcjet, { createMiddleware, shield } from "@arcjet/next";export const config = { // The matcher prevents the middleware executing on static assets and the // /api/hello API route because you already installed Arcjet directly matcher: ["/((?!_next/static|_next/image|favicon.ico|api/hello).*)"],};const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});// Pass any existing middleware with the optional existingMiddleware propexport default createMiddleware(aj);Pages & Server Actions
Arcjet can be used inside Next.js middleware, API routes, pages, server components, and server actions. Client components cannot be protected because they run on the client only.
See the Next.js SDK reference for examples of pages / page components and server actions.
Per route vs hooks
Bot protection rules can be configured in two ways:
- Per route: The rule is defined in the route handler itself. This allows you to configure the rule alongside the code it is protecting which is useful if you want to use the decision to add context to your own code. However, it means rules are not located in a single place.
- Hooks: The rule is defined as a hook. This allows you to configure rules in a single place or apply them globally to all routes, but it means the rules are not located alongside the code they are protecting.
Per route
This configures bot protection on a single route.
import { env } from "$env/dynamic/private";import arcjet, { shield } from "@arcjet/sveltekit";import { error, type RequestEvent } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function load(event: RequestEvent) { const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "You are suspicious!"); }
return {};}import { env } from "$env/dynamic/private";import arcjet, { shield } 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: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function load(event) { const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "You are suspicious!"); }
return {};}/>
Hooks
This will run on every request to your SvelteKit app - see the SvelteKit Hooks docs for details.
import { env } from "$env/dynamic/private";import arcjet, { shield } from "@arcjet/sveltekit";import { error } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function handle({ event, resolve }) { const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "Forbidden"); }
return resolve(event);}import { env } from "$env/dynamic/private";import arcjet, { shield } 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: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
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);}Avoiding double protection with hooks
If you use Arcjet in hooks and individual routes, you need to be careful that Arcjet is not running multiple times per request. This can be avoided by excluding the individual routes before running Arcjet in the hook.
For example, if you already have a shield rule defined in the API route
at /api/arcjet, you can exclude it from the hook like this:
import { env } from "$env/dynamic/private";import arcjet, { shield } from "@arcjet/sveltekit";import { error } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function handle({ event, resolve }) { // Ignore routes that extend the Arcjet rules // - they will call `.protect` themselves const filteredRoutes = ["/api/arcjet"]; if (filteredRoutes.includes(event.url.pathname)) { // return - route will handle protecttion return resolve(event); }
// Ensure every other route is protected with shield const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "Forbidden"); }
// Continue with the route return resolve(event);}import { env } from "$env/dynamic/private";import arcjet, { shield } 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: [ // Protect against common attacks with Arcjet Shield shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function handle({ event, resolve,}: { event: RequestEvent; resolve: (event: RequestEvent) => Response | Promise<Response>;}): Promise<Response> { // Ignore routes that extend the Arcjet rules // - they will call `.protect` themselves const filteredRoutes = ["/api/arcjet"]; if (filteredRoutes.includes(event.url.pathname)) { // return - route will handle protection return resolve(event); }
// Ensure every other route is protected with shield const decision = await aj.protect(event);
if (decision.isDenied()) { return error(403, "Forbidden"); }
// Continue with the route return resolve(event);}Decision
Arcjet provides a single protect function that is used to execute your
protection rules. This requires a RequestEvent property which is the event
context as passed to the request handler.
If you are using a global guard or per route
guard then protect is called for you behind the scenes. If you add Arcjet
within a route then you call it directly.
This function returns a Promise that resolves to an
ArcjetDecision object. This contains the following properties:
id(string) - The unique ID for the request. This can be used to look up the request in the Arcjet dashboard. It is prefixed withreq_for decisions involving the Arcjet cloud API. For decisions taken locally, the prefix islreq_.conclusion(ArcjetConclusion) - The final conclusion based on evaluating each of the configured rules. If you wish to accept Arcjet’s recommended action based on the configured rules then you can use this property.reason(ArcjetReason) - An object containing more detailed information about the conclusion.results(ArcjetRuleResult[]) - An array ofArcjetRuleResultobjects containing the results of each rule that was executed.ip(ArcjetIpDetails) - An object containing Arcjet’s analysis of the client IP address. See the SDK reference for more information.
You check if a deny conclusion has been returned by a shield rule by using
decision.isDenied() and decision.reason.isShield() respectively.
You can iterate through the results and check whether a shield rule was applied:
for (const result of decision.results) { console.log("Rule Result", result);}This example will log the full result as well as the shield rule:
import arcjet, { fixedWindow, shield } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return new Response("Forbidden", { status: 403 }); }
return new Response("Hello world"); }),};import arcjet, { fixedWindow, shield } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return new Response("Forbidden", { status: 403 }); }
return new Response("Hello world"); }),};import arcjet, { fixedWindow, shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Tracking by ip.src is the default if not specified //characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function POST(req: Request) { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return NextResponse.json({ error: "Forbidden" }, { status: 403 }); }
return NextResponse.json({ message: "Hello world", });}import arcjet, { fixedWindow, shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Tracking by ip.src is the default if not specified //characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function POST(req) { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return NextResponse.json({ error: "Forbidden" }, { status: 403 }); }
return NextResponse.json({ message: "Hello world", });}import arcjet, { fixedWindow, shield } from "@arcjet/next";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Tracking by ip.src is the default if not specified //characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export default async function handler(req, res) { const decision = await aj.protect(req); console.log("Decision", decision);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return res .status(403) .json({ error: "Forbidden", reason: decision.reason }); }
res.status(200).json({ name: "Hello world" });}import arcjet, { fixedWindow, shield } from "@arcjet/next";import type { NextApiRequest, NextApiResponse } from "next";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Tracking by ip.src is the default if not specified //characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export default async function handler( req: NextApiRequest, res: NextApiResponse,) { const decision = await aj.protect(req); console.log("Decision", decision);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return res .status(403) .json({ error: "Forbidden", reason: decision.reason }); }
res.status(200).json({ name: "Hello world" });}import { env } from "$env/dynamic/private";import arcjet, { fixedWindow, shield } from "@arcjet/sveltekit";import { error, json, type RequestEvent } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY!, rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function GET(event: RequestEvent) { const decision = await aj.protect(event);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return error(403, "Forbidden"); }
return json({ message: "Hello world" });}import arcjet, { fixedWindow, shield } from "@arcjet/sveltekit";import { error, json } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY, rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function GET(event) { const decision = await aj.protect(event);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { return error(403, "Forbidden"); }
return json({ message: "Hello world" });}import arcjet, { shield, fixedWindow } from "@arcjet/remix";import type { LoaderFunctionArgs } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function loader(args: LoaderFunctionArgs) { const decision = await aj.protect(args);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield protection rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { throw new Response("Too Many Requests", { status: 429, statusText: "Too Many Requests", }); } else { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); } }
return null;}import arcjet, { shield, fixedWindow } from "@arcjet/remix";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://app.arcjet.com characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
export async function loader(args) { const decision = await aj.protect(args);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield protection rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { throw new Response("Too Many Requests", { status: 429, statusText: "Too Many Requests", }); } else { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); } }
return null;}import arcjet, { fixedWindow, shield } 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 characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
const server = http.createServer(async function (req, res) { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { res.writeHead(429, { "Content-Type": "application/json" }); res.end( JSON.stringify({ error: "Too Many Requests", reason: decision.reason }), ); res.end(JSON.stringify({ error: "Forbidden" })); } else { 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, { fixedWindow, shield } 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 characteristics: ["ip.src"], rules: [ fixedWindow({ mode: "LIVE", window: "1h", max: 60, }), shield({ mode: "LIVE", }), ],});
const server = http.createServer(async function ( req: http.IncomingMessage, res: http.ServerResponse,) { const decision = await aj.protect(req);
for (const result of decision.results) { console.log("Rule Result", result);
if (result.reason.isRateLimit()) { console.log("Rate limit rule", result); }
if (result.reason.isShield()) { console.log("Shield rule", result); } }
if (decision.isDenied()) { if (decision.reason.isRateLimit()) { res.writeHead(429, { "Content-Type": "application/json" }); res.end( JSON.stringify({ error: "Too Many Requests", reason: decision.reason }), ); res.end(JSON.stringify({ error: "Forbidden" })); } else { 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, type ArcjetNest, detectBot, shield } from "@arcjet/nest";import { Controller, Get, HttpException, HttpStatus, Inject, Injectable, Logger, Req,} from "@nestjs/common";import type { Request } from "express";
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageService { message(): { message: string } { return { message: "Hello world", }; }}
// This would normally go in your controller file e.g.// src/page/page.controller.ts@Controller("page")// Sets up the Arcjet protection without using a guard so we can access the// decision and use it in the controller.export class PageController { // Make use of the NestJS logger: https://docs.nestjs.com/techniques/logger // See // https://github.com/arcjet/example-nestjs/blob/ec742e58c8da52d0a399327182c79e3f4edc8f3b/src/app.module.ts#L29 // and https://github.com/arcjet/example-nestjs/blob/main/src/arcjet-logger.ts // for an example of how to connect Arcjet to the NestJS logger private readonly logger = new Logger(PageController.name);
constructor( private readonly pageService: PageService, @Inject(ARCJET) private readonly arcjet: ArcjetNest, ) {}
@Get() async index(@Req() req: Request) { const decision = await this.arcjet .withRule( 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: [], // blocks all automated clients }), ) .withRule( shield({ mode: "LIVE", }), ) .protect(req);
this.logger.log(`Arcjet: id = ${decision.id}`); this.logger.log(`Arcjet: decision = ${decision.conclusion}`);
for (const result of decision.results) { this.logger.log("Rule Result", result);
if (result.reason.isShield()) { this.logger.log("Shield rule", result); }
if (result.reason.isBot()) { this.logger.log("Bot protection rule", result); } }
if (decision.isDenied()) { if (decision.reason.isBot()) { throw new HttpException("No bots allowed", HttpStatus.FORBIDDEN); } else { throw new HttpException("Forbidden", HttpStatus.FORBIDDEN); } }
return this.pageService.message(); }}Error handling
Arcjet is designed to fail open so that a service issue or misconfiguration does
not block all requests. The SDK will also time out and fail open after 1000ms
when NODE_ENV or ARCJET_ENV is development and 500ms otherwise. However,
in most cases, the response time will be less than 20-30ms.
If there is an error condition, Arcjet will return an
ERROR type and you can check the reason property for more information, like
accessing decision.reason.message.
import arcjet, { shield } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ shield({ mode: "LIVE", }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return new Response("Service unavailable", { status: 503 }); }
if (decision.isDenied()) { return new Response("You are suspicious!", { status: 403 }); }
return new Response("Hello world"); }),};import arcjet, { shield } from "@arcjet/bun";import { env } from "bun";
const aj = arcjet({ key: env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ shield({ mode: "LIVE", }), ],});
export default { port: 3000, fetch: aj.handler(async (req) => { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return new Response("Service unavailable", { status: 503 }); }
if (decision.isDenied()) { return new Response("You are suspicious!", { status: 403 }); }
return new Response("Hello world"); }),};import arcjet, { shield } from "@arcjet/remix";import type { LoaderFunctionArgs } from "@remix-run/node";
const aj = arcjet({ key: process.env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com rules: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function loader(args: LoaderFunctionArgs) { const decision = await aj.protect(args);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes // throw new Response("Service unavailable", { status: 503, statusText: "Service unavailable" }); }
if (decision.isDenied()) { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); }
return null;}import arcjet, { shield } from "@arcjet/remix";
const aj = arcjet({ key: process.env.ARCJET_KEY, // Get your site key from https://app.arcjet.com rules: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
export async function loader(args) { const decision = await aj.protect(args);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes // throw new Response("Service unavailable", { status: 503, statusText: "Service unavailable" }); }
if (decision.isDenied()) { throw new Response("Forbidden", { status: 403, statusText: "Forbidden" }); }
return null;}import { env } from "$env/dynamic/private";import arcjet, { shield } from "@arcjet/sveltekit";import { error, json, type RequestEvent } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(event: RequestEvent) { const decision = await aj.protect(event);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return error(503, { message: "Service unavailable" }); }
if (decision.isDenied()) { return error(403, { message: "You are suspicious!" }); }
return json({ message: "Hello world" });}import { env } from "$env/dynamic/private";import arcjet, { shield } from "@arcjet/sveltekit";import { error, json } from "@sveltejs/kit";
const aj = arcjet({ key: env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(event) { const decision = await aj.protect(event);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return error(503, { message: "Service unavailable" }); }
if (decision.isDenied()) { return error(403, { message: "You are suspicious!" }); }
return json({ message: "Hello world" });}import arcjet, { shield } from "@arcjet/next";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export default async function handler(req, res) { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return res.status(503).json({ error: "Service unavailable" }); }
if (decision.isDenied()) { return res.status(403).json({ error: "You are suspicious!", }); }
res.status(200).json({ name: "Hello world" });}import arcjet, { shield } from "@arcjet/next";import type { NextApiRequest, NextApiResponse } from "next";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export default async function handler( req: NextApiRequest, res: NextApiResponse,) { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return res.status(503).json({ error: "Service unavailable" }); }
if (decision.isDenied()) { return res.status(403).json({ error: "You are suspicious!", }); }
res.status(200).json({ name: "Hello world" });}import arcjet, { shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY!, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(req: Request) { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return NextResponse.json({ error: "Service unavailable" }, { status: 503 }); }
if (decision.isDenied()) { return NextResponse.json( { error: "You are suspicious!", // Useful for debugging, but don't return it to the client in // production //reason: decision.reason, }, { status: 403, }, ); }
return NextResponse.json({ message: "Hello world", });}import arcjet, { shield } from "@arcjet/next";import { NextResponse } from "next/server";
const aj = arcjet({ key: process.env.ARCJET_KEY, rules: [ shield({ mode: "LIVE", }), ],});
export async function GET(req) { const decision = await aj.protect(req);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //return NextResponse.json({ error: "Service unavailable" }, { status: 503 }); }
if (decision.isDenied()) { return NextResponse.json( { error: "You are suspicious!", // Useful for debugging, but don't return it to the client in // production //reason: decision.reason, }, { status: 403 }, ); }
return NextResponse.json({ message: "Hello world", });}import arcjet, { shield } 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: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
const server = http.createServer(async function (req, res) { const decision = await aj.protect(req); console.log("Arcjet decision", decision);
if (decision.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //res.writeHead(503, { "Content-Type": "application/json" }); //res.end(JSON.stringify({ error: "Service unavailable" })); }
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, { shield } 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: [ shield({ mode: "LIVE", // will block requests. Use "DRY_RUN" to log only }), ],});
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.isErrored()) { // Fail open by logging the error and continuing console.warn("Arcjet error", decision.reason.message); // You could also fail closed here for very sensitive routes //res.writeHead(503, { "Content-Type": "application/json" }); //res.end(JSON.stringify({ error: "Service unavailable" })); }
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, type ArcjetNest, shield } from "@arcjet/nest";import { Controller, Get, HttpException, HttpStatus, Inject, Injectable, Logger, Req,} from "@nestjs/common";import type { Request } from "express";
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageService { message(): { message: string } { return { message: "Hello world", }; }}
// This would normally go in your controller file e.g.// src/page/page.controller.ts@Controller("page")// Sets up the Arcjet protection without using a guard so we can access the// decision and use it in the controller.export class PageController { // Make use of the NestJS logger: https://docs.nestjs.com/techniques/logger // See // https://github.com/arcjet/example-nestjs/blob/ec742e58c8da52d0a399327182c79e3f4edc8f3b/src/app.module.ts#L29 // and https://github.com/arcjet/example-nestjs/blob/main/src/arcjet-logger.ts // for an example of how to connect Arcjet to the NestJS logger private readonly logger = new Logger(PageController.name);
constructor( private readonly pageService: PageService, @Inject(ARCJET) private readonly arcjet: ArcjetNest, ) {}
@Get() async index(@Req() req: Request) { const decision = await this.arcjet .withRule( shield({ mode: "LIVE", }), ) .protect(req);
if (decision.isDenied()) { throw new HttpException("Forbidden", HttpStatus.FORBIDDEN); } else if (decision.isErrored()) { if (decision.reason.message.includes("missing User-Agent header")) { // Requests without User-Agent headers can not be identified as any // particular bot and will be marked as an errored decision. Most // legitimate clients always send this header, so we recommend blocking // requests without it. this.logger.warn("User-Agent header is missing"); throw new HttpException("Bad request", HttpStatus.BAD_REQUEST); } else { // Fail open to prevent an Arcjet error from blocking all requests. You // may want to fail closed if this controller is very sensitive this.logger.error(`Arcjet error: ${decision.reason.message}`); } }
return this.pageService.message(); }}import { ARCJET, type ArcjetNest, shield } from "@arcjet/nest";import { Controller, Get, HttpException, HttpStatus, Inject, Injectable, Logger, Req,} from "@nestjs/common";import type { Request } from "express";
// This would normally go in your service file e.g.// src/page/page.service.ts@Injectable()export class PageService { message(): { message: string } { return { message: "Hello world", }; }}
// This would normally go in your controller file e.g.// src/page/page.controller.ts@Controller("page")// Sets up the Arcjet protection without using a guard so we can access the// decision and use it in the controller.export class PageController { // Make use of the NestJS logger: https://docs.nestjs.com/techniques/logger // See // https://github.com/arcjet/example-nestjs/blob/ec742e58c8da52d0a399327182c79e3f4edc8f3b/src/app.module.ts#L29 // and https://github.com/arcjet/example-nestjs/blob/main/src/arcjet-logger.ts // for an example of how to connect Arcjet to the NestJS logger private readonly logger = new Logger(PageController.name);
constructor( private readonly pageService: PageService, @Inject(ARCJET) private readonly arcjet: ArcjetNest, ) {}
@Get() async index(@Req() req: Request) { const decision = await this.arcjet .withRule( shield({ mode: "LIVE", }), ) .protect(req);
if (decision.isDenied()) { throw new HttpException("Forbidden", HttpStatus.FORBIDDEN); } else if (decision.isErrored()) { if (decision.reason.message.includes("missing User-Agent header")) { // Requests without User-Agent headers can not be identified as any // particular bot and will be marked as an errored decision. Most // legitimate clients always send this header, so we recommend blocking // requests without it. this.logger.warn("User-Agent header is missing"); throw new HttpException("Bad request", HttpStatus.BAD_REQUEST); } else { // Fail open to prevent an Arcjet error from blocking all requests. You // may want to fail closed if this controller is very sensitive this.logger.error(`Arcjet error: ${decision.reason.message}`); } }
return this.pageService.message(); }}Testing
Arcjet runs the same in any environment, including locally and in CI. You can
use the mode set to DRY_RUN to log the results of rule execution without
blocking any requests.
We have an example test framework you can use to automatically test your rules. Arcjet can also be triggered based using a sample of your traffic.
See the Testing section of the docs for details.