BPG converter is a library that allows you to use the new BPG image format transparently converting all the bpg images to png

Usage no npm install needed!

<script type="module">
  import bpgConverter from 'https://cdn.skypack.dev/bpg-converter';


This library enable BPG support in the browser, it is based on ServiceWorker and it fallbacks nicely on unsupported browsers.

BPG Converter installs a ServiceWorker that enables the browser to transparently convert BPG images to PNG. Images encoded with BPG are super small while extremely detailed - visual comparison.


Launch the demo of BPG-Converter and check the DevTools, this is more or less what you'll see on the first access, when the ServiceWorker is still being activated:

First Load

Now reload the page, now the ServiceWorker is active and you'll see something like this

with ServiceWorker

The same image in BPG is just 15Kb, compared to 1Mb of the PNG counterpart!


  • Download the package using npm install bpg-converter --save
  • Create a worker.js file in the root of your project containing:
  • Register the Service Worker from your app using the following code:
if ('serviceWorker' in navigator) {
    navigator.serviceWorker.register('/worker.js', {scope: '/'});
  • Done! Have a look at the next session to learn how to properly setup the images.

How it works

Every time a request is issued for an image with extension .bpg.png the ServiceWorker intercepts the request and looks for the same image without the .png extension - so if the request is for someimage.bpg.png the server will receive an HTTP GET for someimage.bpg. It is important to have both the .bpg.png and the .bpg version on the server in order to be able to deal with browsers that does not support ServiceWorker or to serve images on first access, when the ServiceWorker is still not active.