How To Limit Your API Using Express JS

What is Express Rate Limit?

Basic rate-limiting middleware for Express. Use to limit repeated requests to public APIs and endpoints such as password reset.

Prerequisites

A good understanding javascript basics
Understanding how handle requests
Understanding of how to build REST APIs in NodeJS
Understanding middleware in NodeJS

What Should I Do?

Installing Packages

First of all you need to run the command npm init -y and create a default package.json.

Then you need to install another packages :

Express
Express Rate Limit
Nodemon

npm install express express-rate-limit nodemon

Setup Express

First of all you need to edit package.json to change “scripts”, so following the example below :

"scripts": {
                     "dev": "nodemon server.js",
                     "start": "node server.js"
                    },

If you run npm run dev you will run development server but if you run npm run start it will run production server.

Then you need to create file , name your file whatever you want but i always created file with the name app,js or server,js. following the example below :

// Import express
                        const express = require("express");
                        
                        // Executed express
                        const app = express();
                        
                        const port = process.env.PORT || 3000;
                        
                        app.get("/", () => {
                        return res.send("API");
                        });
                        
                        app.listen(port, () => {
                        console.log(`App running on port ${port}`);
                        });

Setup Express Rate Limit

Since we already added the express-rate-limit in the first step we just need to import it, First we need to import the express-rate-limit in our code below express import.

// Import express
                    const express = require("express");
                    // Import express-rate-limit
                    const rateLimit = require('express-rate-limit');

Then we can configure the time box (windowMs) in milliseconds and the maximum number of requests per IP address (max).

/ Import express
                const express = require("express");
                const rateLimit = require("express-rate-limit");
                
                // Express Limit
                
                // Executed express
                const app = express();
                
                const port = process.env.PORT || 3000;
                
                // Limit requests from same API
                const limiter = rateLimit({
                max: 4, // limit each IP to 4 requests per windowMs
                windowMs: 2 * 60 * 1000, // 2 minute
                message: "Too many requests from this IP, please try again in 2 minute!", // it will display when you hit the limit
                });
                
                //middleware use to limit API
                app.use(limiter);
                
                app.get("/", (req, res) => {
                return res.send("API");
                });
                
                app.listen(port, () => {
                console.log(`App running on port ${port}`);
                });

Default response before we hit the limit.

After you hit the limit it will display a custom message that you write but i write it Too many requests from this IP, please try again in 2 minute!".

Yay! you made it so far!