Microsoft Scott Guthrie flanked by Xamarin's Nat Friedman (l.) and Miguel de Icaza.
Microsoft

But why should anyone write for Windows Phones?

By Barb Darrow
March 31, 2016

Last month, Microsoft finally bought mobile software developer Xamarin after months and months of discussion. Now it’s putting Xamarin’s popular mobile development tools into (what else?) its Visual Studio toolkit.

Even the free Visual Studio community edition will include all of Xamarin and Xamarin Studio for Mac OS X, according to Microsoft corporate vice president Julia Liuson. “We want to make this technology available to as many developers as possible.”

This is an interesting development since Visual Studio has been a mainstay of the Microsoft-centric Windows and .NET world, which has long viewed Apple aapl iPhones as the enemy.

The inclusion of Xamarin, which makes it easier for mobile developers to write code that runs across different devices, including iPhones and Android devices, is thus an eyebrow raiser, although Microsoft msft has been doing its best to show the world that it is no longer “just” focused on Windows machines. That’s probably because Windows Phones have fared poorly in the market compared to the Android and iPhone juggernauts.

In addition, Microsoft is open-sourcing the Xamarin software development kit (SDK) and making it freely available.

Non-techies may not know this but when Microsoft unveiled Visual Studio more than a decade ago, it pretty much upended a development universe in which software tooling was disjointed and expensive. By adding a free version of Xamarin to what has been a bundle of Windows-centric tools, it is making a statement in mobile development as well, said IDC analyst Al Hilwa.

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The idea here is to enable development of lots of mobile apps that will (Microsoft hopes) hook into its Azure cloud. The independent Xamarin was cloud agnostic—it partnered with IBM ibm on Bluemix, Oracle orcl , and Amazon amzn Web Services. Liuson told Fortune that will not change.

Although it’s long been popular to promise developers that they can write an application once and have it run across different operating systems, the reality is typically far different, Liuson acknowledged. To take full advantage of each operating system’s perks, some different code must be written. Xamarin’s promise is that 75% or more of the code running across Android, iOS, and Windows can be shared. The rest will have to be tweaked.

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Windows Phones still lag behind the market, but Liuson said Microsoft is betting that Windows as a whole will succeed: If a developer writes an application for the desktop, that application can also target other devices running Windows.

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San Francisco-based Xamarin employs about 400 people who are now part of Microsoft. Co-founder Nat Friedman is now a Microsoft corporate vice president reporting to executive vice president Scott Guthrie. Friedman’s Xamarin co-founder Miguel de Icaza is also at Microsoft.

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