The Firefox OS Simulator add-on is a tool that enables you to test and debug your Firefox OS app on the desktop. The code-test-debug cycle is much faster with the simulator than with a real device, and of course, you don’t need a real device in order to use it.

Add Firefox OS Simulator to your firebox.


An online playground for your JavaScript, HTML, CSS. JsFiddle is the perfect solution for developers to quick coding and sharing with others.

Write a simple code like “Hello Word” in the jsFiddle.

#<h1>Hello World</h1>

Then, append /manifest.webapp to the end of your Fiddle URL. Check the example.

App manifest

An Open Web App manifest contains information that a Web browser needs to interact with an app. A manifest is one of the key things that distinguish an Open Web App from a website. It is a JSON file with a name and description for the app, and it can also contain the origin of the app, icons, and the permissions required by the app, among other things.

Install the App in the Simulator

Paste the URL that you copied into the field as shown below.

Please note that the simulator will not accept any URLs where the protocol is not specified, so don’t forget to add the ‘http//’. After adding, the simulator should boot your app immediately.

Using JSFiddle for Firefox OS Apps