Microsoft open-sources WSL
At Build 2025, Microsoft finally open-sourced the Windows Subsystem for Linux (WSL), answering a request developers have had since 2016. This move opens the door to broader community involvement and signals Microsoft’s growing commitment to open-source collaboration.
WSL allows users to run full Linux distributions inside Windows without the need for dual-boot setups or bulky virtual machines. Since its 2016 debut, it has become essential for developers, especially those working with Linux-based workflows. It enables seamless use of Linux command-line tools, utilities, and even graphical applications directly on Windows.
The first version, WSL 1, used a compatibility layer to translate Linux calls for the Windows kernel, which made it slow. WSL 2, released in 2019, brought major improvements by introducing a real Linux kernel running in a lightweight virtual machine. This boosted performance and expanded support for a wider range of Linux features.
Now, Microsoft has released most of WSL’s code under the MIT License on GitHub. This includes tools like wsl.exe, wslg.exe, wslconfig.exe, the WSL service responsible for managing distros and networking, and Linux-side components handling port forwarding and file sharing. Some parts, like the legacy lxcore.sys driver used in WSL 1 remains closed.
The delay in open-sourcing WSL stemmed from the challenge of untangling it from core Windows code. Microsoft credits the community for shaping WSL even before the source code was public. Today, WSL supports numerous distributions, including Ubuntu, Fedora, Debian, Kali, and Arch, all runnable side-by-side on Windows 10 or 11. According to StackOverflow’s 2024 survey, 16.8% of developers use WSL more than several native Linux distributions, hardening its place as a vital tool in modern development.
