Firefox OS 2.5 Developer Preview, an experimental Android app

Mozilla launched Firefox OS 2.5 Developer Preview earlier today, and is now offering the operating system as an app on Android. The experimental app replaces several elements of the Android homescreen with Firefox's web-based offering, and even comes with a set of system apps for phone calls, messages, emails, and even an app store. Think of it as a launcher with a set of bundled apps.

Here's the breakdown of what's new in Firefox OS 2.5:

• Add-ons: Just like the add-ons we've come to love in desktop browsers, Firefox OS add-ons can extend just one app, several, or all of them, including the system app itself.
• Private Browsing with Tracking Protection: A new Firefox privacy feature, Tracking Protection allows users to control how their browsing activity is tracked across many sites.
• Pin the Web: Pin the Web removes the artificial distinction between web apps and web sites and lets you pin any web site or web page to your home screen for later usage.

Mozilla mentions that it employed workarounds to provide a consistent user experience to those on Android, and as such you'll find that the Android navigation buttons are overlaid atop the UI. However, you can't use the back button for navigation, as Firefox OS employs a single home button.

Given the nature of the app, it is available as a directly downloadable APK from the link below. Should you like what you see, you can also flash the OS on your handset.

Download Firefox OS 2.5