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QRCode / 2d Barcode api with both server side and client side support using canvas

Build Status


This is a server side QR code/2d barcode generator.

It is an extension of "QRCode for JavaScript" which Kazuhiko Arase thankfully MIT licensed.

The qrcode-draw.js can be used directly as a client side lib if its appended too or included with lib/qrcode.js.

To use this on the server side please require('qrcode'); =)


A simple server side test...

var QRCode = require('qrcode');
QRCode.toDataURL('i am a pony!',function(err,url){

In your terminal if you install globally...

qrcode "hi i want a qrcode"
qrcode "i like to save qrs to file" qr.png

In client side HTML...

<!--[if ie]><script type="text/javascript" src="/vendors/excanvas/excanvas.js"></script><![endif]-->
<script src="/build/qrcode.js"></script>
<canvas id="test"></canvas>
var qrcodedraw = new QRCodeLib.QRCodeDraw();
qrcodedraw.draw(document.getElementById('test'),"this text will be in the code!", function(error,canvas){
     return console.log('Error =( ',error);

Remember to put excanvas.js and qrcode.js somewhere where your browser can find them.

Server Side API

QRCode.draw(text, [optional options], cb(error,canvas));

Returns a node canvas object see for all of the cool node things you can do. Look up the canvas api for the other cool things.

QRCode.toDataURL(text, [optional options], cb(error,dataURL));

SVG output!

QRCode.drawSvg(text, [optional options],cb(error, svgString)); 

Returns mime image/png data url for the 2d barcode., text, [optional options] , cb(error,written));

Saves png to the path specified returns bytes written.

QRCode.drawText(text, [optional options],cb)

Returns an ascii representation of the qrcode using unicode characters and ansi control codes for background control.

QRCode.drawBitArray(text, [optional options], cb(error,bits,width));

Returns an array with each value being either 0 light or 1 dark and the width of each row. This is enough info to render a qrcode any way you want. =)



Can be one of the values in qrcode.errorCorrectLevel. Can be a string. one of "minimum","medium","high","max". If undefined, defaults to H which is max error correction. If invalid value, defaults to minimum error correction.

client side api


qrcodelib.qrcodedraw() Constructor

qrcode = new qrcodelib.qrcodedraw()
qrcode.draw(canvasElement,text,[optional options],cb);

For quick client side use...

node test/clientsideserver.js
open http://localhost:3031

The JavaScript is in test/clientside.html.

QR code capacity

This libary can encode this many bytes at each error correct level:

  • 2953 in error correct level L
  • 2331 in error correct level M
  • 1663 in error correct level Q
  • 1273 in error correct level H

The default is H.

please note as pointed out by @giacecco that byte length is often greater than string length due to multibyte characters.

// so use the byte length 
(new Buffer(str)).length
// instead of the string length 

It can now be changed in an ugly way that wont be supported for more then another few days if you really need to. Also the default module size at qr version 40 is really too small for the camera on my Nexus 1 and to make it larger i run out of screen to show it. At 40 the barcode scanner even finds random UPC 1d barcodes in the mass of little squares. the default module size cannot be changed through the public api at this time.


npm install qrcode

To use qrcode from the command line to save qrcode images or generate ones you can view in your terminal...

npm install -g qrcode

node-canvas is a native module and requires dev packages of cairo and pixman to compile. On ubuntu you can install them with apt-get and npm install will work great.

sudo apt-get install libpixman-1-dev libcairo2-dev libpangocairo-1.0-0 libpango1.0-dev libgif-dev  libjpeg-dev

i would like to switch to a js only image encoder to remove these deps.


These should be taken care of for you by npm but you should...

npm install canvas

If cairo gives you trouble and you cannot install canvas, checkout the canvas site. I know @tjholowaychuk has setup a way to download and install a version of cairo/pixman for testing.

The word "QR Code" is registered trademark of:


GS1 qrcodes

there was a real good discussion here about them. but in short any qrcode generator will make gs1 compatable qrcodes, but what defines a gs1 qrcode is a header with metadata that describes your gs1 information.