Rate limiting with throttler in NestJS - Mini Project: Build & Apply

Rate limiting with throttler

📖 Scenario: You are building a simple NestJS API that needs to protect its endpoints from too many requests in a short time. This helps keep the server stable and fair for all users.

🎯 Goal: Build a NestJS controller with rate limiting using the @nestjs/throttler package. You will set up the data, configure the rate limit, apply the throttler to an endpoint, and complete the setup so the API limits requests properly.

📋 What You'll Learn

Create a NestJS controller named AppController with a GET endpoint /hello that returns a greeting string.

Add a configuration variable ttl (time to live) set to 60 seconds for the rate limit window.

Use the @Throttle decorator to limit the /hello endpoint to 5 requests per ttl seconds.

Complete the module setup by importing ThrottlerModule with the ttl and limit values.

💡 Why This Matters

🌍 Real World

Rate limiting is used in real APIs to prevent abuse and keep services stable by limiting how often users can call endpoints.

💼 Career

Understanding how to implement rate limiting with NestJS and throttler is important for backend developers building scalable and secure APIs.

1

Create the controller with a simple GET endpoint

Create a NestJS controller class named AppController. Inside it, add a method getHello decorated with @Get('hello') that returns the string 'Hello, world!'.

NestJS

import { Controller, Get } from '@nestjs/common';

// Your code here

Need a hint?

Use @Controller() to mark the class as a controller. Use @Get('hello') above the method that returns the greeting string.

2

Add a configuration variable for rate limit time window

Add a constant variable named ttl and set it to 60. This will represent the time window in seconds for rate limiting.

NestJS

import { Controller, Get } from '@nestjs/common';

const ttl = 60; // Time window in seconds

// Your code here

Need a hint?

Declare const ttl = 60; at the top level before the controller class.

3

Apply the @Throttle decorator to limit requests

Import @Throttle from @nestjs/throttler. Add the decorator @Throttle(5, ttl) above the getHello method to limit it to 5 requests per 60 seconds.

NestJS

import { Controller, Get } from '@nestjs/common';
import { Throttle } from '@nestjs/throttler';

const ttl = 60;

@Controller()
export class AppController {
  @Get('hello')
  // Your code here
  getHello(): string {
    return 'Hello, world!';
  }
}

Need a hint?

Use @Throttle(5, ttl) just above the getHello method.

4

Complete the module setup with ThrottlerModule import

Import ThrottlerModule from @nestjs/throttler. In your module file, add ThrottlerModule.forRoot({ ttl, limit: 5 }) to the imports array of the @Module decorator to enable global throttling.

NestJS

import { Module } from '@nestjs/common';
import { ThrottlerModule } from '@nestjs/throttler';
import { AppController } from './app.controller';

const ttl = 60;

@Module({
  imports: [
    // Your code here
  ],
  controllers: [AppController],
})
export class AppModule {}

Need a hint?

Use ThrottlerModule.forRoot({ ttl, limit: 5 }) inside the imports array of @Module.