what is webp image file format

WebP Image File Format

WebP file is a next-gen image format employing both lossy and lossless compression. It is true-color graphics on the web, producing smaller files of comparable image quality to the older JPEG scheme. In this tutorial, you are going to know what is WebP file image extension and how to open WebP extensions on Windows or Mac, how to convert the format, and what systems support the .webp file type like WordPress.

Read: How to Compress Image Without Losing Visible Quality

What Browsers Support WebP files?

Google Chrome, Firefox, Opera, GNOME Web, Midori, and Falkon natively support WebP image format in new versions.

Edge HTML-based versions of Microsoft Edge support through a platform extension (installed by default), but not when running in the Application Guard mode. Since versions of Microsoft Edge released after January 2020 are based on the Chromium browser, WebP support is built-in without the need for platform extensions.

Safari added support for WebP with iOS 14 and the upcoming macOS Big Sur.

It can also be displayed in all major browsers using the WebP JS JavaScript library, although support in Internet Explorer 6 and above is achieved using Flash.

Supported Android

Lossy WebP images are supported in Android 4.0 (API level 14) and higher, and lossless and transparent WebP images are supported in Android 4.3 (API level 18) and higher.

How to Open WebP File?

Often when you download an image, it comes with a WEBP extension and you cannot open it with your regular applications. So, what do you do then?

Because WebP is developed by Google and is royalty-free, it has already been integrated into lots of applications and software you might already have on your computer. Most web browsers already have the required plugin to handle the format.

You can also open WEBP files with applications bundled with the Windows and macOS operating systems:

  • In Windows, Microsoft Paint supports WebP images and you may also be able to open WebP images with Microsoft Photos by renaming their file extension to .jpg (this allows Photos to recognize the file as an image; it does not alter the internal formatting).
  • In macOS, Apple Preview supports WebP images.

If you are an Android, iOS, or Chrome OS user, you can open WEBP files with Google Photos. You can also upload WebP images to Google Photos to view them with the web application.

Using in HTML

Using this format in HTML is like using any other kind of image.

<img src="img/myimage.webp" alt="WebP Image" />

Some browsers don’t support this format. To solve this issue, use the <picture> tag to display images.

  <source srcset="img/myimage.webp" type="image/webp">
  <source srcset="img/myimage.jpg" type="image/jpeg"> 
  <img src="img/myimage.jpg" alt="Not WebP Image">

This is probably your best bet for the broadest possible compatibility because it will work in every single browser, not just those that support the <picture> element.

Using in CSS

Unlike the element in HTML which falls back gracefully to the <img> element in all browsers, CSS doesn’t provide a built-in solution for fallback images that’s optimal.

Modernizr is a well-known feature detection library that detects available features in browsers. When you add this custom build to your website via the <script> tag, it will automatically add one of two classes to the <html> element:

  • The “webp” class is added when the browser supports it.
  • The “no-webp” class is added when the browser doesn’t support it.

With these classes, you’ll be able to use CSS to load background images according to a browser’s capability by targeting the class on the tag:

.no-webp .elementWithBackgroundImage {
  background-image: url("myimage.jpg");

.webp .elementWithBackgroundImage{
  background-image: url("myimage.webp");

How to Use WebP when JavaScript is Disabled

If you’re depending on Modernizr, you have to think about those users who have JavaScript disabled.

To get around this, we’ll start by adding a class of no-js to the <html> tag:

<html class="no-js">

We’ll then write a small piece of inline script that we’ll place before any other scripts:


This will remove the no-js class on the <html> element when parsed.

When JavaScript is disabled, this small script never runs, so the no-js class will stay on the element. This means we can add another rule to provide an image type that has the widest support:

.no-js .elementWithBackgroundImage {
  background-image: url("myimage.jpg");

This covers all our bases. If JavaScript is available, the inline script is run and removes the no-js class before the CSS is parsed, so the JPEG is never downloaded in a WebP-capable browser. If JavaScript is indeed turned off, then the class is not removed and the more compatible image format is used.

Converting Images to a WebP image file with Node.js

To convert images with Node.js you need Node installed before. If not, install it.

After installation, go to your project root in the terminal window and install the “imagemin” and the “imagemin-webp” on the project with Node Package Manager.

npm install imagemin imagemin-webp

Now open your text editor and name it “mywebp.js“.

Type the script below into the file:

var imagemin = require("imagemin"),    // The imagemin module.
  webp = require("imagemin-webp"),   // imagemin's WebP plugin.
  outputFolder = "./img",            // Output folder
  PNGImages = "./img/*.png",         // PNG images
  JPEGImages = "./img/*.jpg";        // JPEG images

imagemin([PNGImages], outputFolder, {
  plugins: [webp({
      lossless: true // Losslessly encode images

imagemin([JPEGImages], outputFolder, {
  plugins: [webp({
    quality: 65 // Quality setting from 0 to 100

This script will process all JPEG and PNG images in the “img” folder and convert them to WebP.

This script assumes that all of your JPEG and PNG images are in a folder named “img“. Once you’re ready, run the script like so:

node mywebp.js

Converting Images with PHP

Using the function below you can convert jpeg, jpg, png, and gif format.

function hs_webp_image($file, $compression_quality = 80){
    // check if file exists
    if (!file_exists($file)) {
        return false;

    // If output file already exists return path
    $output_file = basename($file,'.'. pathinfo($file,PATHINFO_EXTENSION)) . '.webp';
    if (file_exists($output_file)) {
        return $output_file;

    $file_type = strtolower(pathinfo($file, PATHINFO_EXTENSION));

    if (function_exists('imagewebp')) {

        switch ($file_type) {
            case 'jpeg':
            case 'jpg':
                $image = imagecreatefromjpeg($file);

            case 'png':
                $image = imagecreatefrompng($file);
                imagealphablending($image, true);
                imagesavealpha($image, true);

            case 'gif':
                $image = imagecreatefromgif($file);
                return false;

        // Save the image
        $result = imagewebp($image, $output_file, $compression_quality);
        if (false === $result) {
            return false;

        // Free up memory

        return $output_file;
    } elseif (class_exists('Imagick')) {
        $image = new Imagick();

        if ($file_type === 'png') {
            $image->setOption('webp:lossless', 'true');

        return $output_file;

    return false;

Read more about our tutorial Convert JPG, PNG, GIF, and, WebP in PHP

Support WebP image Extensions in WordPress

WordPress by default did not support WebP image extensions in older versions but, you can upload WebP images like JPG or PNG. To force WordPress to upload .webp type in older versions, you need to add the function below to the functions.php file.

if (!function_exists('hs_webp_upload_mimes')) {
     function hs_webp_upload_mimes($existing_mimes)
          $existing_mimes['webp'] = 'image/webp';
          return $existing_mimes;
     add_filter('mime_types', 'hs_webp_upload_mimes');

To display the WebP image format in the Media section, we must add the function below in functions.php.

if (!function_exists('hs_webp_is_displayable')) {
     function hs_webp_is_displayable($result, $path)
          if ($result === false) {
               $displayable_image_types = array(IMAGETYPE_WEBP);
               $info = @getimagesize($path);
               if (empty($info)) {
                    $result = false;
               } elseif (!in_array($info[2], $displayable_image_types)) {
                    $result = false;
               } else {
                    $result = true;
          return $result;
     add_filter('file_is_displayable_image', 'hs_webp_is_displayable', 10, 2);

Now you can upload WebP images and see them in the Media section.


Using WebP Images

Upload WebP Image Format on WordPress

Convert images to WebP using PHP