Microsoft Open-Sources Windows Subsystem for Linux in Major Move to Embrace Developer Community

Microsoft Corp (MSFT.O) has officially open-sourced its Windows Subsystem for Linux (WSL), marking a significant shift in the company’s approach to software development and strengthening its relationship with the open-source community. The announcement was made Tuesday at the company’s annual Build developer conference. The release comes nearly nine years after WSL’s debut and includes the majority of the system’s source code, now available on GitHub. Microsoft said the move is aimed at accelerating development and fostering broader collaboration with developers worldwide. Originally launched in 2016, WSL allowed Windows users to run a Linux environment without the need for a virtual machine or dual-boot setup. The first version, WSL 1, operated through a compatibility layer translating Linux system calls for the Windows NT kernel. WSL 2, introduced in 2019, replaced that layer with a full Linux kernel running inside a lightweight virtual machine, greatly enhancing performance and compatibility. The newly open-sourced components include WSL’s core command-line tools, background services, and Linux-side daemons managing features such as networking and port forwarding. Some proprietary elements remain closed, including WSL 1’s `lxcore.sys` driver and parts of the file system redirection stack used to bridge Windows and Linux environments. Pierre Boulay, a senior software engineer at Microsoft, called the open-source release “a new chapter” for WSL, saying it will allow for faster innovation and broader community involvement in the platform’s evolution. > “This has been one of the most requested features since the project began,” Boulay said. “Now, we’re giving developers the tools and access they need to take WSL even further.” The move also fulfills the very first issue ever logged on the WSL GitHub repository back in 2016: a request to make WSL open source. Microsoft’s corporate vice president for Windows, Pavan Davuluri, said the decision required structural changes to decouple WSL from the Windows OS release cycle — a key step that has now been achieved. By removing that dependency, Microsoft said WSL can be updated more frequently and independently, allowing for quicker bug fixes and feature rollouts. The company framed the open-sourcing of WSL as part of a broader effort to position Windows as a best-in-class development platform — one that supports seamless integration of Linux tools and workflows. Microsoft has steadily embraced open-source technologies in recent years, a departure from its historically closed software model. The company has contributed to and acquired open-source projects such as GitHub, and previously made components of .NET, PowerShell, and Visual Studio Code publicly available. Shares of Microsoft were up 0.7% in afternoon trading on the Nasdaq following the announcement. Analysts say the move could strengthen Microsoft's appeal among developers and help it retain relevance in cloud-native and cross-platform development environments. The WSL source code is now available on GitHub for download, inspection, and contribution. Microsoft has encouraged developers to engage with the project and submit improvements, signaling a more open and agile development future for the tool.