How to convert an image to WebP in NodeJS Express Backend

How to convert an image to WebP in NodeJS Express Backend


3 min read

In this article, we will learn how we can convert the uploaded image to NodeJS Express Server to WebP image. Before we dive into code first let's understand Why it's a good idea to convert the image to WebP, and what are the Advantages of it? Let's start.

Why WebP?

WebP is an image extension by Google's Chromium Team, which provide both Lossless and Lossy Image compression with Transparency like PNG

  • Supports Transparency

  • 25% to 34% smaller file size

  • WebP is natively supported in Google Chrome, Safari, Firefox, Edge, the Opera browser, Mobile Apps, and many other tools

  • Reducing image size leads to Improved Performance and faster site loads.

Let's Start by creating Node-Express Project

here is a Full code example if you want to dive into that first

Step 1: Create a Backend project & Install the following dependency

to create a backend project first create a directory,

mkdir image-to-webp-example-nodejs && cd image-to-webp-example-nodejs
npm init

now it's time to install some dependency

npm i express formidable
npm i image-to-webp

This NPM package provides the method to convert the image to a WebP image.

now edit the `package.json` file according to your project needs. make sure you create the empty index.js file

now paste the following code

const fs = require("fs");
const express = require("express");
const formidable = require("formidable");
const { imageToWebp } = require("image-to-webp");

const app = express();"/upload", async (req, res) => {
    const form = formidable({ multiples: false });
    form.parse(req, async (err, fields, files) => {
        if (err) {

        const image = files.image.filepath;

        const webpImage = await imageToWebp(image, 30);

        // now you can copy this file to public directory or simply upload to your cloud storage provider like AWS S3 / Cloudinary / Google Cloud Storage
        fs.copyFileSync(webpImage, "./public/images/myimg.webp");

        res.json({ image, webpImage });

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on the ${PORT}`);

see here I called the imageToWebp method which takes one required parameter which is the input image path. formidable returns the Submitted image path from FormData.

Optionally you can pass the Quality of the output image in the second argument of imageToWebp it accepts the number ranging between 0 to 100.

0 is for High compression and lossy quality. the lesser value means more compression. if you don't pass it, then it will consider 80 as the default.

The imageToWebp return the output WebP image path which is stored in the tmp directory. you should move it to your Public directory to make it accessible to the internet. Or upload the image to any Cloud Provider like S3 / Cloudinary / Google Cloud Storage etc.

I hope you will find it very helpful. I am attaching links here for reference, Thanks for reading.

Source Code

NPM: image-to-webp

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