Windows Subsystem for Linux

Windows Subsystem for Linux (WSL) is a component of Microsoft Windows that allows the use of a GNU/Linux environment from within Windows, foregoing the overhead of a virtual machine and being an alternative to dual booting. The WSL command-line interface tool is installed by default in Windows 11, but a distribution must be downloaded and installed through it before use. In Windows 10, WSL can be installed either by joining the Windows Insider program or manually via Microsoft Store or Winget.

The original version, WSL 1, differs significantly from the second major version, WSL 2. WSL 1 (released August 2, 2016), acted as a compatibility layer for running Linux binary executables (in ELF format) by implementing Linux system calls in the Windows kernel. WSL 2 (announced May 2019), introduced a real Linux kernel – a managed virtual machine (via Hyper-V) that implements the full Linux kernel. As a result, WSL 2 is compatible with more Linux binaries as not all system calls were implemented in WSL 1.

Microsoft offers WSL for a variety of reasons. Microsoft envisions WSL as "a tool for developers – especially web developers and those who work on or with open source projects". Microsoft also claims that "WSL requires fewer resources (CPU, memory, and storage) than a full virtual machine" (a common alternative for using Linux in Windows), while also allowing the use of both Windows and Linux tools on the same set of files.

The majority of WSL was released as open source software on May 19, 2025, although certain filesystem functions still rely on a proprietary library that is not open source at this time.