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This is a NodeJS module for processing navigator.mozPay() payments on a server.

You'll need to obtain a secret key from a provider such as the Firefox Marketplace but this module should work with any compliant provider. Here is a guide to setting up payments with Firefox Marketplace.

The basic payment flow goes like this:

  • A user clicks a buy button on your app
  • Your app signs a JSON Web Token (JWT) describing the product, the price, and postback/chargeback URLs.
  • Your app client fetches the JWT from the server and calls navigator.mozPay()
  • Your server receives a JWT at its postback or chargeback URL
  • If the postback was received and the JWT signature validates against your secret key then you can disburse your product.


npm install mozpay


The module is intended to be used server side only because you can't expose your secret key to the client. There are helpers to hook into an express app but you could probably use other web frameworks too.

Load the module:

var pay = require('mozpay');

Configure it when your app starts up:

  // This is your Application Key from the Firefox Marketplace Devhub.
  mozPayKey: '52ee5d47-9981-40ad-bf6e-bca957f65385',
  // This is your Application Secret from the Firefox Marketplace Devhub.
  mozPaySecret: 'd6338705419ea14328084e0c182603ebec4e52c1c6cbceda4d61ee125f10c0f728c4451a4637e4e960b3293df8bb6ac5',
  // This is the aud (audience) in the JWT. You only need to override this if you want to use a dev server.
  mozPayAudience: '',
  // This is an optional prefix to your postback/chargeback URLs.
  // For example, a postback would be available at https://yourapp/mozpay/postback with the default prefix.
  mozPayRoutePrefix: '/mozpay',
  // Set a custom payment type for JWTs. You only need to override this if
  // you're working with a non-default payment provider.
  mozPayType: 'mozilla/payments/pay/v1',
  // This is an optional list of JWT algorithms to support when verifying
  // messages from the Firefox Markeplace. It defaults to HS256 only since
  // that's what the Marketplace uses.
  supportedAlgorithms: ['HS256'],

With an express 4 app object, add your routes:

var express = require('express');
var bodyParser = require('body-parser');
var pay = require('mozpay');
var app = express();

  // Make sure you turn on the body parser for POST params.

app.use(bodyParser.urlencoded({ extended: false }));

You can test your postback/chargeback URLs with something like this:

curl -X POST -d notice=JWT http://localhost:3000/mozpay/postback
curl -X POST -d notice=JWT http://localhost:3000/mozpay/chargeback

If you see a 400 Bad Request response then your app is configured to receive real JWT requests.

You can combine the configuration and routes setup like this:

pay.routes(app, {
  mozPayKey: '52ee5d47-9981-40ad-bf6e-bca957f65385',
  mozPaySecret: 'd6338705419ea14328084e0c182603ebec4e52c1c6cbceda4d61ee125f10c0f728c4451a4637e4e960b3293df8bb6ac5',
  // ...


Here's how to take action when the postback notices are received. The data argument to these event handlers are only for valid JWT notices that pass the signature verification.

pay.on('postback', function(data) {
  console.log('product ID ' + + ' has been purchased');
  console.log('Transaction ID: ' + data.response.transactionID);

pay.on('chargeback', function(data) {
  console.log('product ID ' + + ' failed');
  console.log('reason: ' + data.response.reason);
  console.log('Transaction ID: ' + data.response.transactionID);

The data.request object is a copy of what you initiated the payment request with.

Issuing Payment Requests

When a user clicks the buy button you should fetch a JWT from the server via Ajax. You can't cache JWTs for too long because they have a short expiration (generally about an hour).

There is a helper to created a JWT to begin a payment. On your server create a URL that does something like this:

var jwt = pay.request({
  id: 'your-unique-product-id',
  name: 'Your Product',
  description: 'A little bit more about the product...',
  pricePoint: 1,  // Consult the Firefox Marketplace price points for details.
                  // This expands to a price/currency at the time of payment.
  productData: 'session_id=xyz',  // You can track whatever you like here.
  // These must be absolute URLs like what you configured above.
  postbackURL: 'http://localhost:3000/mozpay/postback',
  chargebackURL: 'http://localhost:3000/mozpay/chargeback'

In your client-side JavaScript, you can initiate a payment with the JWT like this:

var request = navigator.mozPay([jwtFromServer]);
request.onsuccess = function() {
  console.log('navigator.mozPay() finished');
  // The product has not yet been bought!
  // Poll your server until a valid postback has been received.
request.onerror = function() {
  console.log('navigator.mozPay() error: ' +;


Grab the source:

git clone git://

Install the dependencies:

cd mozpay-js
npm install

Here's how to run the tests:

npm test