Microsoft says the Windows Subsystem for Linux is now open source, and the company's own announcement gives the change a long backstory. The code that powers WSL is now available on GitHub in the Microsoft/WSL repository, where developers can download it, build it from source, add fixes and features, and participate in the project's active development. That move turns a long-running Windows feature into a visible open-source codebase rather than a black box shipped only as part of the operating system.
The announcement is careful about scope. WSL is a collection of distribution components, and some of them still run in Windows while others run inside the WSL 2 virtual machine. Microsoft says the open-source release does not mean every related component has moved out of the Windows image. Some pieces remain closed at this time. Even so, the key code path for WSL itself is now in the open, which is a substantial change for a feature that began life inside Windows.
Microsoft traces the journey back to 2016, when WSL was first announced at BUILD and initially based on a pico process provider called lxcore.sys. That earlier design let Windows run ELF executables natively and implement Linux syscalls inside the Windows kernel. WSL 2 came later, in 2019, after Microsoft concluded that the best compatibility would come from relying on the Linux kernel itself. The company says that is the point where the subsystem evolved into the architecture most users know today.
As WSL matured, Microsoft added GPU support, graphical application support through wslg, and support for systemd. The growth of the community and the feature set eventually pushed the project into its own separate codebase in 2021. Microsoft says that new package first shipped as version 0.47.1 in the Microsoft Store in July 2021, initially as a preview for Windows 11 users. The open-source release is presented as the result of a multiyear effort to prepare that code for wider external access.
The company also points readers to wsl.dev for a component-by-component overview. That matters because the subsystem is no longer a single monolith in the simple sense; it is a set of pieces that bridge Windows and Linux execution, each with its own role. Opening the repository gives outside developers a clearer view of those boundaries and a direct path to contribute changes. It also gives outside contributors a direct place to inspect how Windows and Linux integration has been maintained over time. The source tree now matters as a living interface between two ecosystems, not just as an internal implementation detail.
The practical significance of the release is easy to see. Microsoft has moved from shipping a proprietary subsystem to publishing the code behind a feature that is already part of many developers' workflows. That does not remove the platform boundaries or the closed portions of the Windows image, but it does lower the barrier for inspection and contribution. For a tool that sits at the intersection of Windows and Linux, that change is likely to matter both for users and for the people who maintain the compatibility layer itself.
