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 arcjet
client can be configured with one or more Shield rules, which are
constructed with the shield(options: ShieldOptions)
function and configured by
ShieldOptions
:
mode ?: ArcjetMode | undefined ;
type ArcjetMode = " LIVE " | " DRY_RUN " ;
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 " ;
key : process . env . ARCJET_KEY ! ,
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
import arcjet , { shield } from " @arcjet/remix " ;
import { redirect } from " @remix-run/node " ;
key : process . env . ARCJET_KEY ,
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
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 " ;
envFilePath : " .env.local " ,
key : process . env . ARCJET_KEY ! ,
// Applies to every request
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
// 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.
export class PageController {
constructor ( private readonly pageService : PageService ) {}
return this . pageService . message () ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message () : { message : string } {
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.
export class PageController {
constructor ( private readonly pageService : PageService ) {}
return this . pageService . message () ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message () : { message : string } {
Within route
Call Arcjet from within the route controller to have maximum flexibility.
import { ARCJET , type ArcjetNest , shield } from " @arcjet/nest " ;
import type { Request } from " express " ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageAdvancedService {
message () : { message : string } {
// This would normally go in your controller file e.g.
// src/page/page.controller.ts
// Sets up the Arcjet protection without using a guard so we can access the
// decision and use it in the controller.
export class PageAdvancedController {
private readonly pageService : PageAdvancedService ,
@ Inject ( ARCJET ) private readonly arcjet : ArcjetNest ,
async index (@ Req () req : Request ) {
const decision = await this . arcjet
if ( decision . isDenied ()) {
if ( decision . reason . isShield ()) {
throw new HttpException ( " No attacks allowed " , HttpStatus . FORBIDDEN ) ;
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 " ;
key : process . env . ARCJET_KEY ,
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
// .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 " ;
key : process . env . ARCJET_KEY ! ,
export default async function handler (
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
// .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 " ;
key : process . env . ARCJET_KEY ! ,
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
//reason: decision.reason,
return NextResponse . json ( {
import arcjet , { shield } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ,
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
//reason: decision.reason,
return NextResponse . json ( {
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 " ;
// 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).*) " ] ,
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet Shield
mode : " LIVE " , // will block requests. Use "DRY_RUN" to log only
// 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 , shield } from " @arcjet/next " ;
// 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).*) " ] ,
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet Shield
mode : " LIVE " , // will block requests. Use "DRY_RUN" to log only
// Pass any existing middleware with the optional existingMiddleware prop
export 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 " ;
// 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).*) " ] ,
key : process . env . ARCJET_KEY ! ,
// Pass any existing middleware with the optional existingMiddleware prop
export 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 " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet 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! " ) ;
import { env } from " $env/dynamic/private " ;
import arcjet , { shield } from " @arcjet/sveltekit " ;
import { error } from " @sveltejs/kit " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet 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! " ) ;
/>
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 " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet 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 " ) ;
import { env } from " $env/dynamic/private " ;
import arcjet , { shield } from " @arcjet/sveltekit " ;
import { error , type RequestEvent } from " @sveltejs/kit " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet Shield
mode : " LIVE " , // will block requests. Use "DRY_RUN" to log only
export async function handle ({
resolve : ( event : RequestEvent ) => Response | Promise < Response >;
const decision = await aj . protect ( event ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
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 " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet 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
// 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
import { env } from " $env/dynamic/private " ;
import arcjet , { shield } from " @arcjet/sveltekit " ;
import { error , type RequestEvent } from " @sveltejs/kit " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
// Protect against common attacks with Arcjet Shield
mode : " LIVE " , // will block requests. Use "DRY_RUN" to log only
export async function handle ({
resolve : ( event : RequestEvent ) => 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
// 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
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 with req_
for decisions
involving the Arcjet cloud API. For decisions taken locally, the prefix is
lreq_
.
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 of ArcjetRuleResult
objects
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 " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
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 " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 " ;
key : process . env . ARCJET_KEY ! ,
// Tracking by ip.src is the default if not specified
//characteristics: ["ip.src"],
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 ( {
import arcjet , { fixedWindow , shield } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ,
// Tracking by ip.src is the default if not specified
//characteristics: ["ip.src"],
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 ( {
import arcjet , { fixedWindow , shield } from " @arcjet/next " ;
key : process . env . ARCJET_KEY ,
// Tracking by ip.src is the default if not specified
//characteristics: ["ip.src"],
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 ()) {
. 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 " ;
key : process . env . ARCJET_KEY ! ,
// Tracking by ip.src is the default if not specified
//characteristics: ["ip.src"],
export default async function handler (
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 ()) {
. 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 " ;
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 " ;
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 " ;
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
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 " , {
statusText : " Too Many Requests " ,
throw new Response ( " Forbidden " , { status : 403 , statusText : " Forbidden " } ) ;
import arcjet , { shield , fixedWindow } from " @arcjet/remix " ;
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
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 " , {
statusText : " Too Many Requests " ,
throw new Response ( " Forbidden " , { status : 403 , statusText : " Forbidden " } ) ;
import arcjet , { fixedWindow , shield } from " @arcjet/node " ;
import http from " node:http " ;
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
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 " } ) ;
JSON . stringify ( { error : " Too Many Requests " , reason : decision . reason } ) ,
res . end ( JSON . stringify ( { error : " Forbidden " } )) ;
res . writeHead ( 403 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { error : " Forbidden " } )) ;
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { message : " Hello world " } )) ;
import arcjet , { fixedWindow , shield } from " @arcjet/node " ;
import http from " node:http " ;
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
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 " } ) ;
JSON . stringify ( { error : " Too Many Requests " , reason : decision . reason } ) ,
res . end ( JSON . stringify ( { error : " Forbidden " } )) ;
res . writeHead ( 403 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { error : " Forbidden " } )) ;
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { message : " Hello world " } )) ;
import { ARCJET , type ArcjetNest , detectBot , shield } from " @arcjet/nest " ;
import type { Request } from " express " ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message () : { message : string } {
// This would normally go in your controller file e.g.
// src/page/page.controller.ts
// 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
// 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 ) ;
private readonly pageService : PageService ,
@ Inject ( ARCJET ) private readonly arcjet : ArcjetNest ,
async index (@ Req () req : Request ) {
const decision = await this . arcjet
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
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 ) ;
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
// Arcjet Pro plan verifies the authenticity of common bots using IP data.
// Verification isn't always possible, so we recommend checking the decision
// https://docs.arcjet.com/bot-protection/reference#bot-verification
if ( decision . reason . isBot () && decision . reason . isSpoofed ()) {
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 " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
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 " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 " ;
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
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 " } ) ;
import arcjet , { shield } from " @arcjet/remix " ;
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 " } ) ;
import { env } from " $env/dynamic/private " ;
import arcjet , { shield } from " @arcjet/sveltekit " ;
import { error , json , type RequestEvent } from " @sveltejs/kit " ;
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 " ;
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 " ;
key : process . env . ARCJET_KEY ,
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 " ;
key : process . env . ARCJET_KEY ! ,
export default async function handler (
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 " ;
key : process . env . ARCJET_KEY ! ,
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
//reason: decision.reason,
return NextResponse . json ( {
import arcjet , { shield } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ,
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
//reason: decision.reason,
return NextResponse . json ( {
import arcjet , { shield } from " @arcjet/node " ;
import http from " node:http " ;
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 " } )) ;
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { message : " Hello world " } )) ;
import arcjet , { shield } from " @arcjet/node " ;
import http from " node:http " ;
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
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 " } )) ;
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
res . end ( JSON . stringify ( { message : " Hello world " } )) ;
import { ARCJET , type ArcjetNest , shield } from " @arcjet/nest " ;
import type { Request } from " express " ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message () : { message : string } {
// This would normally go in your controller file e.g.
// src/page/page.controller.ts
// 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
// 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 ) ;
private readonly pageService : PageService ,
@ Inject ( ARCJET ) private readonly arcjet : ArcjetNest ,
async index (@ Req () req : Request ) {
const decision = await this . arcjet
if ( decision . isDenied ()) {
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
} else if ( decision . isErrored ()) {
// 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 type { Request } from " express " ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message () : { message : string } {
// This would normally go in your controller file e.g.
// src/page/page.controller.ts
// 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
// 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 ) ;
private readonly pageService : PageService ,
@ Inject ( ARCJET ) private readonly arcjet : ArcjetNest ,
async index (@ Req () req : Request ) {
const decision = await this . arcjet
if ( decision . isDenied ()) {
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
} else if ( decision . isErrored ()) {
// 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.