Microsoft open-sources Windows Subsystem for Linux (WSL) and publishes code on GitHub

Microsoft announced at the Microsoft Build 2025 event held on May 20, 2025 that it has open sourced Windows Subsystem for Linux (WSL), a system for running the Linux kernel inside a virtual machine, and released the source code on GitHub.

The Windows Subsystem for Linux is now open source - Windows Developer Blog
https://blogs.windows.com/windowsdeveloper/2025/05/19/the-windows-subsystem-for-linux-is-now-open-source/

GitHub - microsoft/WSL: Windows Subsystem for Linux
https://github.com/microsoft/WSL

'The code that powers WSL has been published on GitHub at Microsoft/WSL and open-sourced to the community. You can download WSL, build it from source, add new fixes and features, and get involved in active development of WSL,' Microsoft said.

WSL was announced at Microsoft Build in 2016 and first released with the Windows 10 Anniversary Update. At the time, WSL was based on the Windows NT kernel driver LxCore.sys, which allowed Windows to run ELF format executables natively and implement Linux system calls within the Windows kernel. This eventually became known as 'WSL 1', which is still supported at the time of writing.

However, it was decided that relying on the Linux kernel itself was important to achieve optimal compatibility with native Linux, and so WSL 2, which runs the Linux kernel directly, was released in 2019.

Microsoft reveals plans to include a complete Linux kernel in Windows - GIGAZINE

In 2021, WSL was separated from the Windows code base and was first released in the Microsoft Store as version 0.47.1 in July 2021. Microsoft said, 'To keep up with our growing community and feature requests, we realized we needed to develop WSL more quickly and release it separately from Windows.'

This Microsoft Store version of WSL initially only supported Windows 11, but support for Windows 10 was added in November 2022, and the stable version 1.0.0 was released.

The Microsoft Store version of 'Windows Subsystem for Linux (WSL)', which runs Linux apps on Windows, has finally reached the official version - GIGAZINE

Then, in September 2023, version 2.0.0 was released, which introduced major improvements such as mirrored networks, DNS tunneling, session 0 support, proxy support, and firewall support. At the time of writing, the latest version is version 2.5.7, the pre-release version of which was released on GitHub this time.

Microsoft commented, 'WSL would not be what it is today without the community. Even without access to the WSL source code, people have made significant contributions that have led to WSL being what it is today. That's why we're so pleased to open source WSL today.'