Example grunt file for building an nwjs desktop app package.

gruntfile.js

module.exports = function(grunt) {
  // Project configuration.
  grunt.initConfig({
    nwjs: {
        options: {
            platforms: ['win64', 'osx64'],
            buildDir: './builds',
            macZip: true
        },
        src: ['../myapp/**/*']
    },

    zip: {
      'win': {
        cwd: 'builds/myapp/win64/',
        src: ['builds/myapp/win64/**'],
        dest: 'builds/myapp/win64/win64.zip',
      },
      'osx64': {
        cwd: 'builds/myapp/osx64/',
        src: ['builds/myapp/osx64/**'],
        dest: 'builds/myapp/osx64/osx64.zip',
      }
    },

    bgShell: {
      _defaults: {
        bg: false
      },

      flatten: {
        cmd: 'flatten-packages ../myapp'
      }
    }
  });

  // Load the plugin that provides the "node-webkit" task.
  grunt.loadNpmTasks('grunt-nw-builder');
  grunt.loadNpmTasks('grunt-zip');
  grunt.loadNpmTasks('grunt-bg-shell');

  // Default task(s).
  grunt.registerTask('default', ['bgShell', 'nwjs', 'zip']);
};

package.json

{
  "name": "myappGrunt",
  "version": "0.0.1",
  "engines": {
    "node": "*",
    "npm": "*"
  },
  "devDependencies": {
    "grunt": "0.4.*",
    "grunt-nw-builder": "*",
    "grunt-zip": "*",
    "grunt-bg-shell": "*"
  }
}