WinToUSB lets you install and run Windows on an external hard drive or USB flash drive
WinToUSB is a lightweight, user-friendly tool that enables you to create and run bootable Windows installations on USB drives or external hard drives. It provides a convenient solution for portable Windows systems or emergency recovery tools. WinToUSB (also called Windows To USB) is a free Windows To Go (WTG) creator that lets you install and run a fully functional version of Windows on an external hard drive, USB flash drive, or Thunderbolt drive. It is simple and efficient – just three steps