GParted Live

GParted Live exists to solve one specific, common problem safely: resizing or reorganizing disk partitions is risky to do from within a running operating system that's actively using those same partitions, so GParted Live boots an entirely separate minimal environment from a USB/CD, letting the partition table be modified with no operating system holding a lock on the disk. It supports resizing, moving, copying, creating, and deleting partitions across most common filesystems (ext4, NTFS, FAT32, Btrfs, and more), making it a standard tool for shrinking a Windows partition to make room for a Linux install, or vice versa. Its interface is deliberately just GParted itself running in a minimal window manager, with essentially nothing else included.