Today we have made Firefox OS 2.5 available worldwide. We are also making an early, experimental build of the OS — Firefox OS 2.5 Developer Preview — available for developers to download on Android devices. This latest version of Firefox OS delivers exciting features including:

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.

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.

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.

To find out more about all aspects of the release, visit Firefox OS v2.5.

Firefox OS 2.5 Developer Preview is an app that lets you experience Firefox OS as an alternate home screen on your Android device without having to re-flash and replace your Android installation. To give it a try, visit the Firefox OS 2.5 Developer Preview, right from your Android device, then click to “Get the Android App.”

Android apps alongside Web apps on the homescreen

Firefox OS Calendar with Android navigation bar

Firefox OS Browser landing page

What is the Firefox OS 2.5 Developer Preview?

You’ve asked how to get involved with the Firefox OS open source project. To date, it’s only been possible to download and explore the latest versions of Firefox OS on specific hardware, such as the Flame device. We’re now working on making Firefox OS more widely available. The Firefox OS Participation Hub provides up-to-date information on getting involved with Firefox OS . The B2G-installer add-on lets you flash a full port of Firefox OS on to an Android device (Note: Firefox OS is under development. Don’t expect it to be bug-free or completely stable.)

Re-flashing existing hardware means losing user data as well as access to Android apps that you may depend on. There’s always an inherent risk of rendering your hardware inoperable, i.e., bricking your device. Firefox OS 2.5 Developer Preview avoids these issues by replacing the Android home screen with the Gaia (UI) layer of Firefox OS. Effectively you can use Firefox OS while still having full access to your Android apps. Firefox OS 2.5 Developer Preview makes Firefox OS available to more developers, testers, localizers, and supporters of the Open Web around the world.

If you’re curious to see what Firefox OS is all about, or just interested in testing out new features, the Firefox OS 2.5 Developer Preview app makes it very simple to get started with very little risk involved. By downloading the app, you can experience Firefox OS and explore many of its capabilities, without flashing hardware. If you decide you’re done trying it out, the app can be removed as simply as any other app. If you’re interested in becoming a code contributor or bug reporter, the app makes it dramatically easier to get involved.

What’s the catch?

As a full operating system, Firefox OS has its own task manager, utility tray, navigation buttons, settings, and more. Running on top of Android means that these elements of the operating system may come into conflict with those same system functions on Android. Android launchers were never designed to enable replacement of these operating system functions. As a result we employ various workarounds, where possible, to avoid delivering a poor user experience. For example, Android uses a back button as a primary navigation method. Firefox OS does not. While we are trying to mitigate these issues, the current edition of the Firefox OS 2.5 Developer Preview app should be considered experimental and will most likely contain bugs. We can certainly use your help in discovering, reporting, and fixing issues.

Hacking on the Firefox OS 2.5 Developer Preview

We’d love for you to play with the Firefox OS 2.5 Developer Preview — to scratch your own itch, test an idea, or contribute to the project by improving performance or finding interesting solutions to the conflict problems with Android system functions mentioned above. With that said, if you are interested in hacking on the app, instructions for building it from scratch can be found here. Alternatively, you can make use of WebIDE in the Firefox Developer Edition browser to start making changes directly to the layout and composition of apps in Firefox OS Developer Preview.

Get involved without coding

There are many ways to get involved without contributing code. The easiest way is to install Firefox OS 2.5 Developer Preview on your Android device and file bugs when you run into problems or discover things that don’t work as expected. If you’re looking for other ways to help, visit our Firefox OS Participation Hub.

Supported devices

The current build will only work on ARM-based devices. It will not work on x86 devices.

Final thoughts

We are very excited about the Firefox OS 2.5 Developer Preview app. We’ve worked hard to produce a Firefox OS experience for Android users. As with all things at Mozilla, this effort is very much a community effort and we welcome all forms of constructive feedback and suggestions for making the experience better.

Got questions about running Firefox OS on new hardware or devices? Try the dev-fxos mailing list or #fxos on IRC. Thanks!