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Microsoft will let developers of different stripes get under the hood and for the first time tinker with one of its crown jewels.

The company said Wednesday that it will release portions of its .NET framework, the foundation many developers use to craft programs for Windows, under an open-source model.

It’s the latest sign of the Redmond company’s shift toward trying to follow potential customers rather than funnel them at all costs to its flagship Windows operating system.

Under open-source licensing, users are free to modify the design of a program and distribute copies. While .NET doesn’t have the same public profile as Windows or the Office suite, with a client base of what Microsoft says is 6 million developers the platform is ubiquitous in that community.

“This helps Microsoft stay relevant to the developers who create applications people want to use,” said Jeffrey Hammond, a vice president and analyst with Forrester Research.

For most of its existence, Microsoft was at the opposite end of the open-source debate, building its software in-house and offering customers only the ability to make use of the finished or semi-finished product. In Microsoft’s ideal scenario that product would run on a Windows-powered device.

Microsoft co-founder Bill Gates helped set the tone for the enduring culture clash between advocates of free and proprietary software development. He wrote an open letter in 1976 to an early group of Silicon Valley PC hobbyists, saying that by making unlicensed copies of Microsoft software they were discouraging developers from spending the time and money to create it in the first place.

The .NET shift is the latest in a string of moves by Microsoft to emphasize the use of its products regardless of what operating system or device users prefer. Chief Executive Satya Nadella has said the company must emphasize serving customers who increasingly interact with software on Internet-based platforms, and with mobile devices, rather than on software installed on PCs.

Microsoft had hinted at its plans for .NET at its conference in April, saying it would allow developers open-source access to the portion of the program that translates programmers’ code into languages computers use to run programs.

In addition to its open-source announcement Wednesday, Microsoft said the .NET framework will also be supported for Apple’s Mac operating system and open-source Linux for the first time. The company also will offer a more-powerful free version of the Visual Studio set of tools used to build programs with .NET for non-business clients.

Analysts say Microsoft is essentially choosing to forgo some immediate sales to individuals now, in the hopes that users come to rely on its products and later pay for add-on services, such as online storage space or enhanced support features. In making .NET open source and available for Mac and Linux, the goal is to make sure that as developers increasingly build programs accessed online from remote servers, they do it on Azure, Microsoft’s cloud-computing platform, and buy Microsoft’s lineup of developer support tools.

Microsoft “recognized that the people who are writing the software that is powering the Internet don’t want to work on a closed, proprietary platform,” said John Sullivan, an executive director of the Free Software Foundation, a nonprofit that advocates free use and modification of software.

Sullivan said it remains to be seen how much of contributions from coders outside the company will deploy in future releases of the product.

Microsoft isn’t opening up all of the .NET code to outside developers. The code underlying most desktop programs users are familiar with, such as audio or video playback, will remain proprietary Microsoft products.

The portions of the code the company did release Wednesday govern foundational functions users don’t typically see, like how servers communicate with each other or how a corporate expense accounting system processes its workflow.

Matt Day: 206-464-2420 or On twitter: @mattmday