Microsoft, a tech company historically known for its opposition to the open source software paradigm, turned to embrace the approach in the 2010s. From the 1970s through 2000s under CEOsBill Gates andSteve Ballmer, Microsoft viewed the community creation and sharing of communal code, later to be known as free and open source software, as a threat to its business, and both executives spoke negatively against it. In the 2010s, as the industry turned towardscloud,embedded, andmobile computing—technologies powered by open source advances—CEOSatya Nadella led Microsoft towards open source adoption although Microsoft's traditional Windows business continued to grow throughout this period generating revenues of 26.8 billion in the third quarter of 2018, while Microsoft'sAzure cloud revenues nearly doubled.[1]
Microsoft open sourced some of its code, including the.NET Framework, and made investments in Linux development, server technology, and organizations, including theLinux Foundation andOpen Source Initiative.Linux-based operating systems power the company'sAzure cloud services. Microsoft acquiredGitHub, the largest host for open source project infrastructure, in 2018. Microsoft is among the site's most active contributors. While this acquisition led a few projects to migrate away from GitHub,[2] this proved a short-lived phenomenon as by 2019 there were over 10 million new users ofGitHub.[citation needed]
Since 2017, Microsoft is one of the biggest open source contributors in the world,[3] measured by the number of employees actively contributing to open source projects on GitHub, the largest host of source code in the world.[4][5]
The paradigm of freely sharing computersource code—a practice known asopen source—traces back to the earliest commercial computers, whose user groups shared code to reduce duplicate work and costs.[6] Following an antitrust suit that forced the unbundling of IBM's hardware and software, a proprietary software industry grew throughout the 1970s, in which companies sought to protect their software products. The technology companyMicrosoft was founded in this period and has long been an embodiment of the proprietary paradigm and its tension with open source practices, well before the terms "free software" or "open source" were coined. Within a year of founding Microsoft,Bill Gates wrote anopen letter that positioned the hobbyist act of copying software as a form of theft.[7]
Microsoft successfully expanded in personal computer and enterprise server markets through the 1990s, partially on the strength of the company's marketing strategies.[8] By the late 1990s, Microsoft came to view the growing open source movement as a threat to their revenue and platform. Internal strategy memos from this period, known as theHalloween documents, describe the company's potential approaches to stopping open source momentum. One strategy was "embrace-extend-extinguish", in which Microsoft would adopt standard technology, add proprietary extensions, and upon establishing a customer base, would lock consumers into the proprietary extension to assert a monopoly of the space. The memos also acknowledged open source as a methodology capable of meeting or exceeding proprietary development methodology. Microsoft downplayed these memos as the opinions of an individual employee and not Microsoft's official position.[9]
While many major companies worked with open source software in the 2000s,[10] the decade was also marked by a "perennial war" between Microsoft and open source in which Microsoft continued to view open source as a scourge on its business[11] and developed a reputation as the archenemy of the free and open source movement.[12] Bill Gates and Microsoft CEOSteve Ballmer suggested free software developers and the Linux kernel were communist.[13][14][15] Ballmer also likenedLinux to a kind of cancer on intellectual property. Microsoftsued Lindows, a Linux operating system that could runMicrosoft Windows applications, as a trademark violation. The court rejected the claim and after Microsoft purchased its trademark, the software changed its name toLinspire.[11]
In 2002, Microsoft began experimenting with 'shared source', including theShared Source Common Language Infrastructure, the core of.NET Framework.[16]
In 1998, Microsoft published at least one public beta release of their Services for UNIX (SFU)[17] based on theMKS toolkit, which in turn included someGNU utilities licensed under theGPL. Microsoft fulfilled the obligations imposed by the GPL and otherOpen Source Software (FLOSS) licenses by offering the source code of these software components and their licenses for download.
Services for UNIX (SFU) v1.0 was released in February 1999.
In April 2004,Windows Installer XML (WiX) was the firstMicrosoft project to be released under an open-source license, theCommon Public License. Initially hosted onSourceForge, it was also the first Microsoft project to be hosted externally.
In June 2004, for the first time Microsoft was represented with a booth atLinuxTag, a free softwareexposition, held annually inGermany.[18] LinuxTag claims to be Europe's largest exhibition for open source software.
In August 2004, Microsoft made the complete source code of theWindows Template Library (WTL) available under theCommon Public License and released it through SourceForge. Since version 9.1, the library is licensed under theMicrosoft Public License.[19]
In September 2004,Microsoft released itsFlexWiki, making its source code available on SourceForge.[20] The engine is open source, also licensed under the Common Public License. FlexWiki was the third Microsoft project to be distributed via SourceForge, after WiX and Windows Template Library.
In 2005, Microsoft released theF#programming language under theApache License 2.0.[16]
In 2006, Microsoft launched itsCodePlex open source code hosting site, to provide hosting for open-source developers targeting Microsoft platforms. In the same year, Microsoft portedPHP to Windows underPHP License[16] and also partnered with and commissioned Vertigo Software to createFamily.Show, a free and open-sourcegenealogy program, as a reference application for Microsoft's latestUI technology andsoftware deployment mechanism at the time,Windows Presentation Foundation andClickOnce.[21][22][23] The source code has been published on CodePlex and is licensed under theMicrosoft Public License.
In November 2006, Microsoft andNovell announced a broad partnership to make sure Windows interoperates withSUSE Linux. The initial agreement endured until 2012 and included promises not to sue over patents as well as joint development, marketing and support of Windows – Linux interoperability solutions. In addition, Microsoft and Novell agreed to work to ensure documents created in the freeOpenOffice.org productivity suite can seamlessly work inOffice 2007, and vice versa. Both companies also agreed to develop on translators to improve interoperability betweenOffice Open XML andOpenDocument formats. The company also purchased 70,000 one-year SUSE Linux Enterprise Server maintenance and update subscription coupons from Novell. Microsoft could distribute the coupons to customers as a way to convince them to choose Novell's Linux rather than a competitor's Linux distribution.[24]
Microsoft CEO Steve Ballmer acknowledged that more customers are running mixed systems and said about the partnership with Novell:
While we're going to compete, we're going to collaborate in the right way.
— Steve Ballmer, CEO of Microsoft[25]
In June 2007,Tom Hanrahan, formerDirector of Engineering at theLinux Foundation, became Microsoft'sDirector of Linux Interoperability.[26][27]TheOpen Source Initiative approved theMicrosoft Public License (MS-PL) andMicrosoft Reciprocal License (MS-RL) in 2007.[16] Microsoft open sourcedIronRuby,IronPython, andxUnit.net under MS-PL in 2007.[16]
In 2008, Microsoft joined theApache Software Foundation[28] and co-founded theOpen Web Foundation with Google, Facebook, Sun, IBM, Apache, and others.[16] Also in 2008, Microsoft began distributing the open sourcejQuery JavaScript library together with theVisual Studio development environment for use within theASP.NET AJAX andASP.NET MVC frameworks.[29][30]
When Microsoft releasedHyper-V in 2008,SUSE Linux Enterprise Server became the first non-Windows operating system officially supported on Hyper-V. Microsoft andNovell signed an agreement to work on interoperability two years earlier.[31]
Microsoft first began contributing to theLinux kernel in 2009.[16] TheCodePlex Foundation, an independent501(c)(6) non-profit corporation founded by Microsoft and led mostly by Microsoft employees and affiliates, was founded in September 2009. Its goal was to "enable the exchange of code and understanding among software companies and open source communities."[32][33] Later in September 2010, the name Outercurve Foundation was adopted.[34]
In November 2009, Microsoft released the source code of the.NET Micro Framework to the development community as free and open-source software under theApache License 2.0.[35]
StyleCop, an originally proprietarystatic code analysis tool by Microsoft, was re-released as an open-source in April 2010 onCodePlex. Based on customer feedback, Microsoft relicensedIronRuby,IronPython, and theDynamic Language Runtime (DLR) underApache License 2.0 in July 2010.[36]
Microsoft signed theJoomla contributor agreement and started upstreaming improvements in 2010.[16]
In 2011, Microsoft started contributing code to theSamba project. The same year, Microsoft also portedNode.js to Windows, upstreaming the code under Apache License 2.0.[16] The first version ofPython Tools for Visual Studio (PTVS) was released in March 2011. After acquiringSkype in 2011, Microsoft continued maintaining the Skype Linux client.[16]In July 2011, Microsoft was the fifth largest contributor to theLinux 3.0 kernel at 4% of the total changes.[37][38] The company became a partner with LinuxTag for their 2011 event and also sponsored LinuxTag 2012.[39][40]
In 2012, Microsoft began hosting Linuxvirtual machines in theAzurecloud computing service andCodePlex introducedgit support.[16] The company also portedApache Hadoop to Windows, upstreaming the code under MIT License.[16] In March 2012, a completely rewritten version ofChronoZoom was made available as open source[41] via theOutercurve Foundation. Also,ASP.NET,ASP.NET MVC,ASP.NET Razor,ASP.NET Web API,Reactive extensions, andIL2JS (anIL to JavaScript compiler) were released under Apache License 2.0.[16] TheTypeScriptprogramming language was released under Apache License 2.0 in 2012. It was the first Microsoft project hosted on GitHub.[16] In June 2012, Microsoft contributedOpen Management Infrastructure toThe Open Group with the goal "to remove all obstacles that stand in the way of implementing standards-based management so that every device in the world can be managed in a clear, consistent, coherent way and to nurture [and] spur a rich ecosystem of standards-based management products."[42]
In 2013, Microsoft relicensed thexUnit.netunit testing tool for the .NET Framework under Apache License 2.0 and transferred it to theOutercurve Foundation.[16] Also in 2013, Microsoft addedGit support toVisual Studio andTeam Foundation Server usinglibgit2, the most widely deployed version of Git. The company is dedicating engineering hours to help further develop libgit2 and working with GitHub and other community programmers who devote time to the software.[43]
In 2014,Satya Nadella was named the new CEO of Microsoft. Microsoft began to adopt open source into its core business. In contrast to Ballmer's stance, Nadella presented a slide that read, "Microsoft loves Linux".[12] At the time of the acquisition of GitHub, Nadella said of Microsoft, "We are all in on open source." As the industry trended towardscloud,embedded, andmobile computing, Microsoft turned to open source to stay apace in these open source dominated fields. Microsoft's adoption of open source included several surprising turns.
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In 2014, the company opened the source of its.NET Framework to promote its software ecosystem and stimulate cross-platform development. Microsoft also started contributing to theOpenJDK the same year.[16] TheWireless Display Adapter, released in 2014, was Microsoft's first hardware device to useembedded Linux.[16]
In the beginning of 2015, Microsoft open sourced theZ3 Theorem Prover, a cross-platformsatisfiability modulo theories (SMT) solver.[44]
Also in 2015, Microsoft co-founded theNode.js Foundation[45] and joined theR Foundation. After completing the acquisition ofRevolution Analytics in 2015,[46] Microsoft integrated the open sourceR programming language intoSQL Server 2016,SQL Server 2017,SQL Server 2019,Power BI,Azure SQL Managed Instance,Azure Cortana Intelligence,Microsoft ML Server andVisual Studio 2017.[47]
The same year, Microsoft also open sourcedMatter Center, Microsoft's legal practice management software and alsoChakra, theMicrosoft EdgeJavaScript engine at the time.[16] Also in 2015, Microsoft releasedWindows 10 with native support for the open-sourceAllJoyn framework, which means that any Windows 10 device can control any AllJoyn-awareInternet of Things (IoT) device in the network.[48] Microsoft has been developing AllJoyn support and contributing code upstream since 2014.[16]
Microsoft opened the keynote speech atAll Things Open in 2015 by stating that:
Microsoft's approach to open today is: Enable, integrate, release, and contribute.
— Mark Russinovich, CTO ofMicrosoft Azure[49]
In August 2015, Microsoft releasedWinObjC, also known as Windows Bridge for iOS, an open-sourcemiddleware toolkit that allowsiOS apps developed inObjective-C to be ported to Windows 10.[50][51][52] On November 18, 2015,Visual Studio Code was released under the proprietary Microsoft License and a subset of its source code was posted toGitHub under theMIT License.[53]
In January 2016, Microsoft becameGold Sponsor of SCALE 14x – the fourteenth annualSouthern California Linux Expo, a major convention.[55]
When Microsoft acquiredXamarin andLinkedIn in 2016, it relicensed theMono framework under MIT License and continued maintaining theKafkastream-processing software platform as open source.[16] Also in 2016, Microsoft introduced theWindows Subsystem for Linux, which lets Linux applications run on the Windows operating system. The company invested in Linux server technology and Linux development to promote cross-platform compatibility and collaboration with open source companies and communities, culminating with Microsoft's platinum sponsorship of theLinux Foundation and seat on its board of directors.[56]
Microsoft releasedSQL Server and the now open sourcePowerShell for Linux.[16] Also, Microsoft began portingSysinternals tools, includingProcDump andProcMon, toLinux.[57]R Tools for Visual Studio were released underApache License 2.0 in March 2016.
In March 2016, Ballmer changed his stance on Linux, saying that he supports his successor Satya Nadella's open source commitments. He maintained that his comments in 2001 were right at the time but that times have changed.[58][59]
Commentators have noted the adoption of open source and the change of strategy at Microsoft:[60]
The company has become an enthusiastic supporter of Linux and of open source and a very active member of many important projects.
— Jim Zemlin, Executive Director ofThe Linux Foundation[61]
AtEclipseCon in March 2016, Microsoft announced that the company is joining theEclipse Foundation as aSolutions Member.[62]
TheBitFunnelsearch engine indexing algorithm and various components of theMicrosoft Bing search engine were made open source by Microsoft in 2016.[63][64]vcpkg, a cross-platform open sourcepackage manager, was released in September 2016.[65]
Microsoft joined theOpen Source Initiative, theCloud Native Computing Foundation, and theMariaDB Foundation in 2017.[16] The Open Source Initiative, formerly a target of Microsoft, used the occasion of Microsoft's sponsorship as a milestone for open source software's widespread acceptance.
TheDebian-basedSONiCnetwork operating system was open sourced by Microsoft in 2017.[66]
Also the same year, the Windows development was moved toGit and Microsoft open sourced theGit Virtual File System (GVFS) developed for that purpose.[67][68] Other contributions to Git include a number of performance improvements useful when working with large repositories.[69][70] Microsoft opened theMicrosoft Store to open source applications and gave the keynote speech at theOpen Source Summit North America 2017 in Los Angeles.[16]
In 2018, the Microsoft CTO of Data spoke with ZDNet about the growing importance of open source stating that:
We meet customers where they are, and in particular if you want Linux we'll give you Linux; if you want MySQL, well we'll give you MySQL; you want NoSQL well we'll give you NoSQL -- that means you need to be part of open source; open source by nature is a community thing.
— Raghu Ramakrishnan, Microsoft CTO of Data[71]
Microsoft becamePlatinum Sponsor and delivered the keynote of the 2018Southern California Linux Expo – the largest community-run open-source and free software conference in North America.[72][73]
Microsoft developed Linux-based operating systems for use with itsAzure cloud services. Azure Cloud Switch supports the Azure infrastructure and is based on open source and proprietary technology, and Azure Sphere powersInternet of things devices. As part of its announcement, Microsoft acknowledged Linux's role in small devices where the full Windows operating system would be unnecessary.[73]
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Also in 2018, Microsoft acquiredGitHub, the largest host for open source project infrastructure. Microsoft is among the site's most active contributors and the site hosts the source code for Microsoft'sVisual Studio Code and .NETruntime system. The company, though, has received some criticism for only providing limited returns to the Linux community, since theGPL license lets Microsoft modify Linux source code for internal use without sharing those changes.[76]
In 2018, Microsoft includedOpenSSH,tar, andcurlcommands in Windows.[77][78] Also, Microsoft releasedWindows Calculator as open source underMIT License on GitHub.[79]
Since 2018, Microsoft has been a sponsor of theAdoptOpenJDK project. It is a drop-in replacement forOracle'sJava/JDK.[80]
In April 2018, Microsoft released the Windows 3.x/Windows NTFile Manager source code licensed under theMIT License.[81][82] In August 2018, Microsoft added support for the open sourcePython programming language toPower BI.[83] In October 2018, Microsoft joined theOpen Invention Network[84] and cross-licensed 60,000 patents with the open source community.[85][86]
In 2019, Microsoft's Windows Subsystem for Linux 2 transitioned from an emulated Linux kernel to a full Linux kernel within avirtual machine, improving processor performance manifold. In-keeping with the GPL open source license, Microsoft will submit[when?][citation needed] its kernel improvements for accommodation into the master, public release.[87]
Also in 2019, Microsoft releasedWindows Terminal,PowerToys, and theMicrosoft C++ Standard Library as open source[16] and transitioned itsEdge browser to use the open sourceChromium as the basis.[88] TheWindows Console infrastructure was open-sourced under theMIT License alongside Windows Terminal.[89]
After publishingexFAT as anopen specification, Microsoft contributed the patents to theOpen Invention Network (OIN), and started upstreaming thedevice driver to theLinux kernel.[16]
AtBuild 2019, Microsoft announced that it is open-sourcing itsQuantum Development Kit, including its Q# compilers and simulators.[90]
In December 2019, Microsoft releasedMicrosoft Teams for Linux. This marked the first time Microsoft released anOffice app for the Linux operating system. The app is available in nativepackages in.deb and.rpm formats.[91] Also in December 2019, afterJS Foundation andNode.js Foundation merged to formOpenJS Foundation, Microsoft contributed the popular cross-platform desktop application development toolElectron to OpenJS Foundation.[92][93]
Project Verona, a memory-saferesearch programming language, was open sourced in January 2020.[94][95] Microsoft releasedDeepSpeed, an open sourcedeep learning optimization library forPyTorch, in February 2020.[96]
In 2020, Microsoft open sourced theJava extension forMicrosoft SQL Server,[16]MsQuic (aWindows NT kernel library for theQUIC general-purposetransport layernetwork protocol),[97]Project Petridish, a neural architecture search algorithm for deep learning,[98] and theFluid Framework for building distributed, real-time collaborative web applications.[99] Microsoft also released the Linux-basedAzure Sphere operating system.[16]
In March 2020, Microsoft acquirednpm, the open source Nodepackage manager. It is the world’s largestsoftware registry with more than 1.3 million packages that have 75 billion downloads a month.[100][101] Also in March 2020,Microsoft together with researchers and leaders from theAllen Institute for AI, theChan Zuckerberg Initiative, theGeorgetown University's Center for Security and Emerging Technhology, and theNational Library of Medicine releasedCORD-19, a public dataset of academic articles aboutCOVID-19 and research related to theCOVID-19 pandemic.[102] The dataset is created through the use oftext mining of the current research literature.[103][104]
After exploring different alternative options and talking with various well-known commercial and open source package manager teams includingChocolatey, Scoop,Ninite and others such as AppGet,Npackd and thePowerShell basedOneGet package manager-manager, Microsoft decided to develop and release the open sourceWindows Package Manager in 2020.[105]
Microsoft was one of the silver sponsors for theX.Org Developer’s Conference 2020 (XDC2020). Microsoft had multiple developers presenting on the opening day.[106]
Microsoft completed the first phase of porting theJavaOpenJDK forWindows 10 on ARM devices in June 2020.[80]
In August 2020, Microsoft became founding member of theOpen Source Security Foundation (OpenSSF), a cross-industry forum for a collaborative effort to improve open sourcesoftware security.[107][108]
In September 2020, Microsoft released theSurface Duo, anAndroid-based smartphone with a Linux kernel.[109] The same month, Microsoft releasedOneFuzz, aself-hostedfuzzing-as-a-service platform that automates the detection ofsoftware bugs.[110] It supports Windows and Linux.[111]
Microsoft is a major contributor to theChromium project with the highest percentage of all non-Google contributors coming from Microsoft (35.2%). The company has contributed 29.4% of all non-Google commits to the source code in 2020.[112]CBL-Mariner, acloud infrastructureoperating system based onLinux and developed by theLinux Systems Group at Microsoft for its edge network services and as part of itsMicrosoft Azure cloud infrastructure was open sourced in 2020.[113][114]
In February 2021, Microsoft made the source code for itsExtensible Storage Engine (ESE) available on GitHub under MIT License.[115] Also in February 2021, Microsoft, together with four other founding companies (AWS,Huawei,Google, andMozilla) formed theRust Foundation as an independent non-profit organization to steward the open sourceRustprogramming language and ecosystem.[116][117] In March 2021, Microsoft became founding member of the newEclipse Adoptium Working Group whose goal is to promote free, open sourceJava runtimes.[118] Microsoft released a preview of theMicrosoft Build of OpenJDK in April 2021. It is available for x64 server and desktop editions of Windows, as well as onLinux andmacOS. The company provides long-term support for this distribution of the OpenJDK.[119] In April 2021, Microsoft also released a Windows 10 test build that includes the ability to run Linuxgraphical user interface (GUI) apps usingWindows Subsystem for Linux 2.[120] In the following month, Microsoft launched an open source project to make theBerkeley Packet Filter work on Windows.[121]
At theWindows 11 announcement event in June 2021, Microsoft showcased the newWindows Subsystem for Android (WSA) that will enable support for theAndroid Open Source Project (AOSP) and will allow users to runAndroid apps on their Windows desktop.[122]
In August 2021, Microsoft announced that it is expanding its partnership to become aStrategic Member at the Eclipse Foundation.[123]
Microsoft released the source code of3D Movie Maker under theMIT License in May 2022,[124][125] following a request by theTwitter userFoone a month earlier.[126] Also in May, Microsoft joined the XDP community and released a new open-sourceExpress Data Path interface for Windows.[127][128]
In August 2022, Microsoft open sourced more than 1,500 of its 3Demoji to let creators remix and customize them. The library is available onFigma and GitHub.[129]
On May 18, 2025, Microsoft releasedMicrosoft Edit, an open-source recreation of theMS-DOS Editor written in theRust programming language for modern versions of Windows.[130]
On November 20, 2025, Microsoft licensed the source code forZork I, Zork II, and Zork III under the MIT License.[131]
Microsoft is either founding member, joining member, contributing member, and/or sponsor of a number of open source related organizations and initiatives. Examples include:
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