Apps with 'Multi boot' feature
YUMI (Your Universal Multiboot Installer), is the successor to our MultibootISOs. It can be used to create a Multiboot Bootable USB Flash Drive containing multiple operating systems, antivirus utilities, disc cloning, diagnostic tools, and more.
Flexible and configurable USB drive multiboot solution which also supports UEFI booting.
SARDU (short for Shardana Antivirus Rescue Disk Utility) creates a multiboot all-in-one USB drive, CD or DVD for free (personal and non commercial use).
Boot-US is an universal boot manager. It allows you to easily use of all your existing operating systems completely independent of each other.
SharpBoot is a small utility for creating multiboot ISO or USB.
BootIt Bare Metal is a boot manager and partition manager software utility.
Ventoy is an open source tool to create bootable USB drive for ISO files.