Wubi () is a discontinued tool that allows users to install Ubuntu within a Windows 7 partition without repartitioning the hard drive. It functions like a standard Windows application, creating a virtual disk file (often root.disk ) on your existing filesystem rather than requiring a dedicated Linux partition. Downloading Wubi for Windows 7 (64-bit)

You can find original Wubi installers for versions up to Ubuntu 14.10 on the Ubuntu releases page by looking for wubi.exe at the bottom of a specific release directory.

Is this WUBI? What is "Installation size" setting for? - Ask Ubuntu

This active fork is recommended for modern needs, supporting newer Ubuntu versions (like 20.04 and 22.04) and providing compatibility for both legacy BIOS and UEFI systems. It is available on the WubiUEFI GitHub repository .

While official support from ended in 2013, you can still find legacy and community-maintained versions:

Wubi automatically detects 64-bit architectures. If you run the installer on a 64-bit system, it will download and install the 64-bit (amd64) version of Ubuntu by default. How to Install Ubuntu via Wubi