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node.js wrapper for cwebp and dwebp binaries from WebP image processing utility


Node.js wrapper for cwebp and dwebp binaries from WebP image processing utility.

npm install cwebp

Getting latest version of WebP

You can get latest WebP source, pre-compiled binaries and installation instructions from its official website, or from its downloads repository.

Linux users may use this installation script to automatically download and install latest WebP binaries:

curl -s | sudo bash

MacOS users may install WebP using MacPorts:

sudo port selfupdate
sudo port install webp

If none of it suit your needs, you may build the WebP utilities yourself.

Alternative ways to install WebP

MacOS users may install webp 0.4.0 using homebrew:

brew install webp

You may also install webp 0.3.x as npm module:

npm install webp

Old versions of WebP (prior to 0.4.1) are not compatible with the latest node-webp version.

If you're using old version of WebP, please, use node-webp 0.1.x.

Check this section for more info about new streaming features of the latest WebP version.

var CWebp = require('cwebp').CWebp;
var DWebp = require('dwebp').DWebp;
var encoder = new CWebp(source_image);
var decoder = new DWebp(source_webp);


// new is optional 
var encoder = CWebp(source_image);
var decoder = DWebp(source_webp);


// Backward-compatibility with cwebp@0.1.x 
var CWebp = require('cwebp');

By default node-webp looks for cwebp and dwebp binary in your $PATH.

var Webp = require('cwebp');
var binPath = require('webp').cwebp;
var webp = new Webp(source, binPath);
var CWebp = require('cwebp').CWebp;
CWebp.bin = require('webp').cwebp;
var encoder = new CWebp(source);
var DWebp = require('cwebp').DWebp;
DWebp.bin = require('webp').dwebp;
var decoder = new DWebp(source);

N.B.: webp npm module provide old webp 0.3.x binaries.

When source is a string node-webp treats it as a file path.

var CWebp = require('cwebp').CWebp;
var DWebp = require('dwebp').DWebp;
var encoder = new CWebp('original.jpeg');
var decoder = new DWebp('converted.webp');

It also accepts Buffers and Streams.

var encoder = new CWebp(buffer);
var decoder = new DWebp(stream);

Note that node-webp will start listening to the data in a source stream only when .write(), .stream() or .toBuffer() is called.

encoder.write('image.webp', function(err) {
    console.log(err || 'encoded successfully');
decoder.write('image.png', function(err) {
    console.log(err || 'decoded successfully');
decoder.toBuffer(function(errbuffer) {
    // ... 
var stream =;
stream.on('error', function(err) {
  // something bad happened 

Different versions of WebP have different level of streaming support:

Feature Older WebP versions WebP 0.4.1 node-webp 0.1.x node-webp 1.x
cwebp stdin streaming no no mock mock
cwebp stdout streaming no native mock native
dwebp stdin streaming no native mock native
dwebp stdout streaming no native mock native

mock means that node-webp acts as if the feature is supported, mocking it using temporary files.

So, converting Stream into a Buffer with node-webp 0.x will cause two temporary files to be created and then removed (one to store input stream, and another to read output buffer from).

Note that node-webp native streaming will work only if your WebP version have native support for the corresponding stream, while mock streaming will work with any version of WebP.

IMPORTANT: If you're using old version of WebP, please, use node-webp 0.1.x.

node-webp supports A+ promises.

encoder.write('image.webp').then(function() {
    // ... 
encoder.toBuffer().then(function(buffer) {
    // ... 
}); {
    // ... 

node-webp uses when.js library.

node-webp provides helper functions for most of cwebp and dwebp conversion options. For the full list of available helpers see methods.json file.

encoder.command('-d', 'dump.pgm');