MultiBoot Live USB | USB Apps
Ventoy – Bootable USB Creator

Ventoy is another neat and intuitive Bootable USB creation software tool. It enables users to quickly create a Multiboot flash drive via a simple drag and drop interface. Simply drag and drop an ISO or multiple ISO files onto your Ventoy prepared USB flash drive and then reboot your PC. Choose to boot from your USB device. Then, from the boot menu, select a an ISO file to launch it. This tool supports both BIOS and UEFI boot. Run ISO files in Live Mode or as Installation media.
XBOOT – Multiboot USB ISO Creator

XBOOT is a Windows based Multiboot ISO USB Creator that can be used to create Live Bootable Custom Flash Drives or Multiboot CDs or DVDs that can be used to boot multiple distributions, antivirus tools, and utilities. XBOOT features a drag and drop interface, and supports many popular Linux live CDs, Antivirus Rescue CDs, and other tools.
SARDU – MultiBoot USB/CD/DVD Builder

SARDU (Shardana Antivirus Rescue Disk Utility), is a MultiBoot Builder created by Davide Costa. It can be used to create a Live MultiBoot USB CD or DVD containing Antivirus Tools, Live Linux Distros, Diagnostics Tools, Windows PE, Windows Vista,7 and even Windows XP Installers.
YUMI – MultiBoot Live USB Creator

YUMI (Your Universal Multiboot Installer), is a MultiBoot Live USB Creation Tool that can be used to quickly and easily build custom bootable USB Flash Drives containing multiple Live Linux distributions, Windows installers, Antivirus tools, system diagnostic, and troubleshooting software of your choosing.