Microsoft just made a crucial startup buy in its Windows 10 march to conquest

Microsoft has purchased Xamarin, a startup that helps developers write apps once and have them work on any smartphone or operating system, according to an official blog entry.

It's a crucial buy for Microsoft, which has been working around the clock to get more apps onto its Windows Store app market - a key part of the Windows 10 operating system.

Customers like JetBlue and Coca-Cola Bottling used Xamarin to save a ton of time and cash. When developers don't have to waste time rewriting the same app for iPhone, Android, or whatever else, they can be much more productive.

Microsoft and Xamarin's history is a long and sometimes shaky one: The two have been longstanding partners, working with joint customers to help them build and power their apps. At one time, Microsoft was thought to be a secret investor in Xamarin's business, leading up to rumors in 2014 that an acquisition was imminent.

"With today's acquisition announcement we will be taking this work much further to make our world class developer tools and services even better with deeper integration and enable seamless mobile app dev experiences," writes Microsoft cloud boss Scott Guthrie in a blog entry.

At the same time, the two companies often came to loggerheads over the best way to serve Microsoft's large and active community of developers.

In late 2015, Xamarin and Oracle signed a deal to bring developers to the Oracle Cloud, which competes with the Microsoft Azure cloud platform. That could have been what finally spurred Microsoft to take action and buy up Xamarin entirely.

Meanwhile, Microsoft has been struggling to attract developers to make apps for the new Windows 10 operating system. With Xamarin, it can now offer customers a new and easier way to bring their apps to Windows, and power it with the Microsoft Azure cloud. It's a big step for Microsoft.

Plus, Xamarin offers its so-called Test Cloud product, which lets developers see how apps perform on any device - Android, iPhone, BlackBerry, or what. All of that gets rolled into Microsoft's business now, making it appealing to developers.