Arcjet Sensitive Information Detection protects against clients sending you
sensitive information such as PII that you do not wish to handle.
Configuration
Sensitive Info is configured by specifying which mode you want it to run in.
The configuration definition is:
type SensitiveInfoOptions = {
mode ?: " LIVE " | " DRY_RUN " ;
allow ?: Array < SensitiveInfoType >; // Cannot be specified if `deny` is present
deny ?: Array < SensitiveInfoType >; // Cannot be specified if `allow` is present
contextWindowSize ?: number ;
detect ?: ( tokens : string [] ) -> Array < SensitiveInfoType | undefined >;
The arcjet
client is configured with one or more sensitiveInfo
rules which take
one or many SensitiveInfoOptions
.
The SensitiveInfoType
enum allows the following values:
EMAIL
CREDIT_CARD
IP_ADDRESS
PHONE_NUMBER
You can also provide a custom detection function to detect other types of
sensitive information (see below).
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.
Global guard
A global guard can be configured in src/app.module.ts
.
import { ArcjetModule , sensitiveInfo } 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';
envFilePath : " .env.local " ,
key : process . env . ARCJET_KEY ! ,
// This allows all sensitive entities other than email addresses
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
//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 " ;
// 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 ) {}
async index (@ Req () req : Request , @ Body () body : string ) {
return this . pageService . message ( body ) ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message ( content : string ) : { message : string ; submittedContent : string } {
submittedContent : content ,
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 , sensitiveInfo } from " @arcjet/nest " ;
import { Body , Injectable , Post , Req } 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.
// This allows all sensitive entities other than email addresses
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
export class PageController {
constructor ( private readonly pageService : PageService ) {}
async index (@ Req () req : Request , @ Body () body : string ) {
return this . pageService . message ( body ) ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message ( content : string ) : { message : string ; submittedContent : string } {
submittedContent : content ,
Within route
Call Arcjet from within the route controller to have maximum flexibility.
import { ARCJET , type ArcjetNest , sensitiveInfo } 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 ( content : string ) : { message : string ; submittedContent : string } {
submittedContent : content ,
// 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 {
private readonly pageService : PageService ,
@ Inject ( ARCJET ) private readonly arcjet : ArcjetNest ,
async index (@ Req () req : Request , @ Body () body : string ) {
const decision = await this . arcjet
// This allows all sensitive entities other than email addresses
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
if ( decision . isDenied ()) {
if ( decision . reason . isBot ()) {
throw new HttpException ( " No bots allowed " , HttpStatus . FORBIDDEN ) ;
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
return this . pageService . message ( body ) ;
Per route vs middleware
Bot protection rules 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
This configures bot protection on a single route.
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
. json ( { error : " Unexpected sensitive info received " } ) ;
// 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 , { sensitiveInfo } 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 . isSensitiveInfo ()) {
. json ( { error : " Unexpected sensitive info received " } ) ;
// 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 , { sensitiveInfo } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ! ,
export async function POST ( req : Request ) {
const decision = await aj . protect ( req ) ;
if ( decision . isDenied () && decision . reason . isSensitiveInfo ()) {
return NextResponse . json (
error : " Unexpected sensitive info received " ,
// Useful for debugging, but don't return it to the client in
// reason: decision.reason,
return NextResponse . json ( {
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ,
export async function POST ( req ) {
const decision = await aj . protect ( req ) ;
if ( decision . isDenied () && decision . reason . isSensitiveInfo ()) {
return NextResponse . json (
error : " Unexpected sensitive info received " ,
// Useful for debugging, but don't return it to the client in
// reason: decision.reason,
return NextResponse . json ( {
Middleware
Create a file called middleware.ts
in your project root (at the same level as
pages
or app
or inside src
):
import arcjet , { createMiddleware , sensitiveInfo } 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
// Prevent your app receiving unexpected sensitive info
// 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 , sensitiveInfo } 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
// Prevent your app receiving unexpected sensitive info
// 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 sensitive info 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 , sensitiveInfo } 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 , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error , type RequestEvent } from " @sveltejs/kit " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
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 , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error } from " @sveltejs/kit " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error } from " @sveltejs/kit " ;
key : env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
// This allows all sensitive entities other than email addresses and those containing a dash character.
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
export async function handle ({ event , resolve }) {
const decision = await aj . protect ( event ) ;
if ( decision . isDenied ()) {
return error ( 400 , " Bad request - sensitive information detected " ) ;
import { env } from " $env/dynamic/private " ;
import arcjet , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error , type RequestEvent } from " @sveltejs/kit " ;
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
// This allows all sensitive entities other than email addresses and those containing a dash character.
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
export async function handle ({
resolve : ( event : RequestEvent ) => Response | Promise < Response >;
const decision = await aj . protect ( event ) ;
if ( decision . isDenied ()) {
return error ( 400 , " Bad request - sensitive information detected " ) ;
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 sensitive info 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 , { detectBot } from " @arcjet/sveltekit " ;
import { error , type RequestEvent } from " @sveltejs/kit " ;
allow : [] , // "allow none" will block all detected bots
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 protecttion
const decision = await aj . protect ( event ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
Decision
Arcjet also provides a single protect
function that is used to execute your
protection rules.
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 sensitive info rule by using
decision.isDenied()
and decision.reason.isSensitiveInfo()
respectively.
You can iterate through the results and check whether a sensitive info 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 sensitive info rule:
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return new Response ( " Forbidden " , { status : 403 } ) ;
return new Response ( " Hello world " ) ;
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return new Response ( " Forbidden " , { status : 403 } ) ;
return new Response ( " Hello world " ) ;
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return NextResponse . json ( { error : " Forbidden " }, { status : 403 } ) ;
return NextResponse . json ( {
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return NextResponse . json ( { error : " Forbidden " }, { status : 403 } ) ;
return NextResponse . json ( {
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
. json ( { error : " Forbidden " , reason : decision . reason } ) ;
res . status ( 200 ) . json ( { name : " Hello world " } ) ;
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info 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 , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
return json ( { message : " Hello world " } ) ;
import arcjet , { sensitiveInfo } 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
return json ( { message : " Hello world " } ) ;
import arcjet , { shield , sensitiveInfo } from " @arcjet/remix " ;
import type { ActionFunctionArgs } from " @remix-run/node " ;
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
export async function action ( args : ActionFunctionArgs ) {
const decision = await aj . protect ( args ) ;
for ( const result of decision . results ) {
console . log ( " Rule Result " , result ) ;
if ( result . reason . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( result . reason . isShield ()) {
console . log ( " Shield protection rule " , result ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
{ error : " Please don't send personal data. " },
return Response . json ( { error : " Forbidden " }, { status : 403 } ) ;
// We don't need to use the decision elsewhere, but you could return it to
import arcjet , { shield , sensitiveInfo } from " @arcjet/remix " ;
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
characteristics : [ " ip.src " ] ,
export async function action ( args ) {
const decision = await aj . protect ( args ) ;
for ( const result of decision . results ) {
console . log ( " Rule Result " , result ) ;
if ( result . reason . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( result . reason . isShield ()) {
console . log ( " Shield protection rule " , result ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
{ error : " Please don't send personal data. " },
return Response . json ( { error : " Forbidden " }, { status : 403 } ) ;
// We don't need to use the decision elsewhere, but you could return it to
import arcjet , { sensitiveInfo } 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 ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Unexpected sensitive info detected " ,
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 , { sensitiveInfo , 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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( result . reason . isShield ()) {
console . log ( " Shield protection rule " , result ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Unexpected sensitive info detected " ,
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 type { Request } from " express " ;
// This would normally go in your service file e.g.
// src/page/page.service.ts
export class PageService {
message ( content : string ) : { message : string ; submittedContent : string } {
submittedContent : content ,
// 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 , @ Body () body : string ) {
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 allows all sensitive entities other than email addresses
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " ] , // Will block email addresses
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 . isSensitiveInfo ()) {
this . logger . log ( " Sensitive info 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 if ( decision . reason . isSensitiveInfo ()) {
" Unexpected sensitive info detected " ,
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
return this . pageService . message ( body ) ;
Custom entity detection
When configuring Arcjet Sensitive Info you can provide a custom detect function,
this enables you to detect entities that we don’t support out of the box using
custom logic.
The function will take a list of tokens and must return a list of either
undefined
, if the corresponding token in the input list is not sensitive, or
the name of the entity if it does match. The number of tokens that are provided
to the function is controlled by the contextWindowSize
option, which defaults
to 1. If you need additional context to perform detections then you can increase
this value.
import arcjet , { sensitiveInfo } from " @arcjet/bun " ;
import { env } from " bun " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return new Response ( " Forbidden " , { status : 403 } ) ;
return new Response ( " Hello world " ) ;
import arcjet , { sensitiveInfo } from " @arcjet/bun " ;
import { env } from " bun " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return new Response ( " Forbidden " , { status : 403 } ) ;
return new Response ( " Hello world " ) ;
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return NextResponse . json ( { error : " Forbidden " }, { status : 403 } ) ;
return NextResponse . json ( {
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return NextResponse . json ( { error : " Forbidden " }, { status : 403 } ) ;
return NextResponse . json ( {
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
. json ( { error : " Forbidden " , reason : decision . reason } ) ;
res . status ( 200 ) . json ( { name : " Hello world " } ) ;
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
import type { NextApiRequest , NextApiResponse } from " next " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
. json ( { error : " Forbidden " , reason : decision . reason } ) ;
res . status ( 200 ) . json ( { name : " Hello world " } ) ;
import arcjet , { sensitiveInfo } from " @arcjet/remix " ;
import type { ActionFunctionArgs } from " @remix-run/node " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
export async function action ( args : ActionFunctionArgs ) {
const decision = await aj . protect ( args ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
{ error : " Please don't send personal data. " },
return Response . json ( { error : " Forbidden " }, { status : 403 } ) ;
// We don't need to use the decision elsewhere, but you could return it to
import arcjet , { sensitiveInfo } from " @arcjet/remix " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
export async function action ( args ) {
const decision = await aj . protect ( args ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
{ error : " Please don't send personal data. " },
return Response . json ( { error : " Forbidden " }, { status : 403 } ) ;
// We don't need to use the decision elsewhere, but you could return it to
import { env } from " $env/dynamic/private " ;
import arcjet , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error , json , type RequestEvent } from " @sveltejs/kit " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
return json ( { message : " Hello world " } ) ;
import arcjet , { sensitiveInfo } from " @arcjet/sveltekit " ;
import { error , json } from " @sveltejs/kit " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 . isSensitiveInfo ()) {
console . log ( " Sensitive info rule " , result ) ;
if ( decision . isDenied ()) {
return error ( 403 , " Forbidden " ) ;
return json ( { message : " Hello world " } ) ;
import arcjet , { sensitiveInfo } from " @arcjet/node " ;
import http from " node:http " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens ) {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY , // Get your site key from https://app.arcjet.com
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 ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Unexpected sensitive info detected " ,
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 , { sensitiveInfo } from " @arcjet/node " ;
import http from " node:http " ;
// This function is called by the `sensitiveInfo` rule to perform custom detection on strings.
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
key : process . env . ARCJET_KEY ! , // Get your site key from https://app.arcjet.com
deny : [ " EMAIL " , " CONTAINS_DASH " ] ,
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 ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Unexpected sensitive info detected " ,
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 " } )) ;
Accessing the body
The Arcjet Sensitive Info rule accesses the request body, so if you also need to
access the body in your application code, you should parse it before calling
protect
. Otherwise, you may see an error Body already read
.
For example, using Express:
import arcjet , { sensitiveInfo } from " @arcjet/node " ;
import express from " express " ;
key : process . env . ARCJET_KEY ! ,
// Body is accessed here first so it can be used in the protect method and
app . post ( " / " , async ( req , res ) => {
const decision = await aj . protect ( req ) ;
if ( decision . isDenied () && decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Sensitive Information Detected " ,
denied : decision . reason . denied ,
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
// We can safely access the body here because it has already been referenced
res . end ( JSON . stringify ( { message : ` You said: ${ req . body }` } )) ;
console . log ( ` Example app listening on port ${ port }` ) ;
import arcjet , { sensitiveInfo } from " @arcjet/node " ;
import express from " express " ;
key : process . env . ARCJET_KEY ,
// Body is accessed here first so it can be used in the protect method and
app . post ( " / " , async ( req , res ) => {
const decision = await aj . protect ( req ) ;
if ( decision . isDenied () && decision . reason . isSensitiveInfo ()) {
res . writeHead ( 400 , { " Content-Type " : " application/json " } ) ;
error : " Sensitive Information Detected " ,
denied : decision . reason . denied ,
res . writeHead ( 200 , { " Content-Type " : " application/json " } ) ;
// We can safely access the body here because it has already been referenced
res . end ( JSON . stringify ( { message : ` You said: ${ req . body }` } )) ;
console . log ( ` Example app listening on port ${ port }` ) ;
import { ARCJET , type ArcjetNest , sensitiveInfo } 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 ( content : string ) : { message : string ; submittedContent : string } {
submittedContent : content ,
// This would normally go in your controller file e.g.
// src/page/page.controller.ts
// This function is called by the`sensitiveInfo` rule to perform custom
function detectDash ( tokens : string [] ) : Array < " CONTAINS_DASH " | undefined > {
return tokens . map ( ( token ) => {
if ( token . includes ( " - " )) {
// 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 , @ Body () body : string ) {
const decision = await this . arcjet
// This allows all sensitive entities other than email addresses
mode : " LIVE " , // Will block requests, use "DRY_RUN" to log only
// allow: ["EMAIL"], Will block all sensitive information types other than email.
deny : [ " EMAIL " , " CONTAINS_DASH " ] , // Will block email addresses and strings containing a dash
this . logger . log ( ` Arcjet: id = ${ decision . id }` ) ;
this . logger . log ( ` Arcjet: decision = ${ decision . conclusion }` ) ;
if ( decision . isDenied ()) {
if ( decision . reason . isSensitiveInfo ()) {
" Unexpected sensitive info detected " ,
throw new HttpException ( " Forbidden " , HttpStatus . FORBIDDEN ) ;
return this . pageService . message ( body ) ;
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 500ms
when NODE_ENV
is production
and 1000ms 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 , { sensitiveInfo } 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 ()) {
" Your request contained unexpected sensitive information! " ,
return new Response ( " Hello world " ) ;
import arcjet , { sensitiveInfo } 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 ()) {
" Your request contained unexpected sensitive information! " ,
return new Response ( " Hello world " ) ;
import { env } from " $env/dynamic/private " ;
import arcjet , { sensitiveInfo } 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 , { sensitiveInfo } 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 , { sensitiveInfo } 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 ( 400 ) . json ( {
error : " Unexpected sensitive info received " ,
res . status ( 200 ) . json ( { name : " Hello world " } ) ;
import arcjet , { sensitiveInfo } 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 ( 400 ) . json ( {
error : " Unexpected sensitive info received " ,
res . status ( 200 ) . json ( { name : " Hello world " } ) ;
import arcjet , { sensitiveInfo } from " @arcjet/next " ;
import { NextResponse } from " next/server " ;
key : process . env . ARCJET_KEY ! ,
export async function POST ( 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 });