The following is a list of code-level reference documentation you'll likely need in developing a Firefox OS app.

Note: The technologies detailed below should work across modern browsers; notes are included below to indicate where this differs.

Note: For a granular, detailed account of what new features have been added in what Firefox OS releases, consult our Firefox OS release notes.

Foundations of a Firefox OS app

A Firefox OS app is simply an Open Web App, but with extra features available such as being installable, and access to device APIs to control hardware and device features such as contacts, alarms, etc.

App manifest
The manifest describes your app. This guide explains how the manifest works and how to create one.
App Installation and Management APIs
The programmatic interface you use for installing apps and managing them.
Working offline
Strategies and technologies you can use to ensure that your app works when there's no network connection available.
Types of apps
This article explains the types of apps: hosted, privileged, and certified. You need privileged or certified apps for access to sensitive device APIs. Privileged and certified apps are packaged apps.
App permissions
Access to device APIs is key to creating many useful apps. Here is what's available and how to access them.

Layout and structure

The building blocks of responsive design
Learn the basics of responsive design, an essential topic for modern app layout.
Media queries
One of the most important technologies in responsive app design is the media query. Media queries allow your app to respond to screen size, resolution, device orientation, and many other environment variables using declarative CSS rules or JavaScript listeners. Also see Using media queries and MediaQueryList.
Mobile first
Often when creating responsive application layouts, it makes sense to create the mobile layout as the default, and build wider layouts on top.
Flexible boxes
CSS flexible boxes let you configure your app's user interface to automatically adjust the positioning and sizes of elements based on the size and orientation of the display.
Note: If you are developing Firefox OS apps, be aware that multi-line flexboxes are supported in Firefox OS 1.3+; for older versions you might have to adopt a simpler layout or provide a fallback.

Drawing and animation

CSS transforms
CSS transforms let you rotate, scale, and zoom HTML content, taking advantage of hardware acceleration where available, all without relying on JavaScript code.
CSS transitions
CSS transitions let you animate changes to your CSS. Once a transition effect is configured, changes to your CSS occur over a period of time instead of instantaneously. This makes it possible to easily and efficiently create a wide variety of visual effects in your apps.
CSS animations
CSS animations let you animate changes to your document on a more fundamental level, using keyframes to precisely configure the animation effect. This also lets you create looping animation effects rather than effects that happen just once, as is the case with transitions, all without relying on JavaScript.
HTML canvas
The HTML <canvas> element provides a 2D graphics workspace for you to draw in. This has many uses, including 2D games.
WebGL
WebGL is a Web-friendly version of OpenGL ES that lets your app offer hardware-accelerated 3D graphics.
SVG
Scalable Vector Graphics (SVG) is a technology that lets you draw graphics using vectors instead of bitmapped images. This is great for scalability, presenting diagrams and charts, and for high-quality, scalable user interfaces.

Firefox OS device APIs

These are emerging Web platform standards and device APIs crucial to Firefox OS app development and to Open Web Apps.

The following table gives the app manifest permissions for hosted and privileged apps. For more information see App permissions.

Manifest permission API name Description Minimum app type required access property Default granted Platform/version supported
alarms Alarm Schedule a notification, or schedule an application to be started. hosted none Allow FxOS 1.0.1
audio-capture

getUserMedia, Web Speech API

 Obtain MediaStream from audio input devices, e.g. microphone. This is needed to allow audio capture in Firefox OS 1.2+. hosted for getUserMedia, privileged for Web Speech API none Prompt for all installed App types for getUserMedia, Allow for Web Speech API. FxOS 1.2 and
Desktop Firefox 20+ for getUserMedia, FxOS 2.5 and Desktop Firefox 44 for Web Speech API.
audio-channel-alarm AudioChannels Alarm clock, calendar alarms. privileged none Allow FxOS 1.0.1
audio-channel-content AudioChannels Music, video. hosted none Allow FxOS 1.0.1
audio-channel-normal AudioChannels UI sounds, Web content, music, radio. hosted none Allow FxOS 1.0.1
audio-channel-notification AudioChannels New email, incoming SMS. privileged none Allow FxOS 1.0.1
browser Browser Enables the app to implement a browser in an iframe. privileged none Allow FxOS 1.0.1
camera Camera

Take photos, shoot video, record audio, and control the camera.

Note: camera was limited to certified apps initially because the app sandbox was preventing access to the camera hardware. Fixed from Firefox OS 2.0 onwards.

privileged in Firefox OS 2.0+ internal/certified up to Firefox OS 1.4

 none Prompt for all installed App types. FxOS 1.0.1-1.4 certified
FxOS 2.0+ privileged
contacts Contacts Add, read, or modify contacts from the address book on the device and read contacts from the SIM. privileged readonly, readwrite, readcreate, or createonly Prompt for all installed App types. FxOS 1.1
Firefox Android 18
desktop-notification mozNotification for Gecko <22, Notification for Gecko 22+ Display a notification on the user's desktop. Note that this has changed, so for Gecko <22 (Firefox OS <1.2) you need to use mozNotification, while for Gecko 22+ (Firefox 1.2+) you need to use Notification. hosted none Prompt for Web content. Allow for all installed App types. FxOS 1.0.1, Android 4.0, Desktop 4.0 for prefixed version
FxOS 1.2, Android 22, Desktop 22 for non-prefixed version
device-storage:music Device Storage Add, read, or modify music files stored on the device. privileged readonly, readwrite, readcreate, or createonly Prompt FxOS 1.0.1
device-storage:pictures Device Storage Add, read, or modify picture files stored on the device. privileged readonly, readwrite, readcreate, or createonly Prompt FxOS 1.0.1
device-storage:sdcard Device Storage Add, read, or modify files stored on the device's SD card. privileged readonly, readwrite, readcreate, or createonly Prompt FxOS 1.0.1
device-storage:videos Device Storage Add, read, or modify video files stored on the device. privileged readonly, readwrite, readcreate, or createonly Prompt FxOS 1.0.1
fmradio FM Radio Control the FM radio. hosted none Allow FxOS 1.0.1
geolocation Geolocation Obtain the current location of the user. hosted none Prompt (even for certified Apps) FxOS 1.0.1, Desktop Firefox 3.5, Android 4.0
input Keyboard Allows the app to act as a virtual keyboard by listening to focus change events in other apps. All IME apps need this permission for sending input keys and updating the value of a input field. privileged none Allow FxOS 1.2
mobileid Mobile identity Allows an app to obtain a verified phone number (MSISDN) after the user selects the number to be shared and gives explicit permission for the app to obtain it. privileged/ none Prompt FxOS 2.0
mobilenetwork Mobile Network Obtain mobile network information (MCC, MNC, etc.). privileged none Allow FxOS 1.0.1
moz-firefox-accounts Firefox Accounts Allows the use of Firefox Accounts when using the navigator.mozId API. privileged none Prompt for all installed App types. FxOS 2.0
nfc NFC API NFC enables an app to transmit data to other devices via near field communication. This permission is required for reading and writing data. Privileged none Allow FxOS 2.2
nfc-share NFC API This permission is just required for sharing tags via NFC. Privileged none Allow FxOS 2.2
nfc-read, nfc-write NFC API These permissions were used to request reading and writing privileges in Firefox OS 2.0/2.1 Was certified/internal at this stage in development. none Allow FxOS 2.0
push Simple Push Enable an app to wake up to receive notification. hosted none Allow FxOS 1.1
speech-recognition Web Speech API Allows an app to use speech recognition. privileged none Allow FxOS 2.5 and Desktop Firefox 44.
systemXHR SystemXHR Allows anonymous (no cookies) cross-origin XHR without the target site having CORS enabled. Similar to the TCP Socket API but restricted to XHR, not just raw sockets, so it is slightly less risky. See XMLHttpRequest. privileged none Allow FxOS 1.0.1
tcp-socket TCP Socket Create TCP sockets and communicate over them. privileged none Allow FxOS 1.0.1,
Desktop (early versions)
video-capture GetUserMedia Obtain MediaStream from video input devices, e.g. camera. This is needed to allow video capture in Firefox OS 1.4+. hosted none Prompt for all installed App types. FxOS 1.4

Note: To declare an app as privileged, you need to put "type" : "privileged" into your app manifest. You don't need to include the type field in your manifest for web apps, as web is the default value.

General Web APIs

Elements, events, network requests, storage and other standard Web APIs

Network requests - send and receive data with XMLHttpRequest
XMLHttpRequest is the DOM API used to send and receive information using HTTP, including for downloading files.
DOM events
The event reference provides a complete list of all the events that can be sent and received to interact with DOM objects.
Touch events
This documentation covers touch events in particular, which of course you are likely to encounter when developing apps for touchscreen devices.
Online & offline events
Allows your app to dynamically respond to changes in network connection availability.
History
Travers and manipulate the historical view state of your app with various commands - helpful in rewinding or advancing the user's current view
Audio
Embedding and manipulation of audio content with the HTML5 Audio Tag
Video
Embedding and manipulation of video content with the HTML5 Video Tag
Geolocation
Enables your app to request the user's current location and listen for location changes.
Screen orientation
Listen for high-level screen orentation changes between various portrait and landscape positions.
Device orientation
Allows your app to detect granular device orientation changes from on-device sensors.
IndexedDB
A database access layer for Web apps that provides a scriptable interface for storing and retrieving large sets of data on the user's device.
Storage
The Storage API family provides various way to persistently store limited amounts of simple data on a user's device.
Web workers
Allows apps to run JavaScript code (which cannot touch the DOM or window object) in background threads to optimize performance and unblock UI rendering

Firefox Marketplace services

These documents and guides will help you learn how to publish your app and manage it on the Firefox Marketplace.

Submission API
The Submission API lets you validate your app, update your app, and fetch information about the apps available to be installed.
Marketplace API
All Marketplace-related documentation is centered here.