The Firefox OS Simulator is a piece of a add on in Firefox that simulates a Firefox OS device, and runs on the desktop. This means that in many cases, you don’t need a real device to test and debug your app. It runs in a window the same size as a Firefox OS device, includes the Firefox OS user interface and built-in apps, and simulates many of the Firefox OS device APIs.
Installing the Firefox Simulator add-on
The Simulator is packaged and distributed as a Firefox add-on. To install it:
Using Firefox, go to the Simulator’s page on addons.mozilla.org.
Click “Add to Firefox”.
Once the add-on has downloaded you will be prompted to install it: click “Install Now”.
This add-on is large (50-70MB), because it bundles a complete simulation of Firefox OS, including its default apps. So it takes multiple seconds for Firefox to install the add-on. Sometimes it takes so long that Firefox’s Unresponsive Script dialog appears. If that happens, press the Continue button to let Firefox continue installing the add-on. It will eventually succeed.
Running the simulator
On the dashboard, On the left side you can see “Simulator Stopped”, Click on it and the simulator will start.
Add a app
To add a packaged app to the Simulator, open the Dashboard, click “Add Directory” and select the manifest file for your app. To add a hosted app, enter a URL in the textbox where it says “URL for page or manifest.webapp”, then click “Add URL”. If the URL points to a manifest, then that manifest will be used. If it doesn’t, the Dashboard will generate a manifest for the URL: so you can add any website as an app just by entering its URL.
Note:This add-on is incompatible with Firefox 26 and greater. Please use the App Manager with the new Simulator add-ons.