Software > Bootloader

★ BootX – Built into every PowerPC-based Mac for booting of Mac OS X.
Chameleon – Built to handle Legacy BIOS booting of Mac OS X.
Chimera – Built to transition from Mac OS X to macOS.
Clover – Built with beginners and professionals in mind.
Enoch – Built with tweaks to improve hardware compatibility.
★ Start Manager – Built into every Intel-based Mac with limits on Apple system software.
OpenCore – Built with the speed and security that your system software needs.
Ozmosis – Built for dual UEFI motherboards and true vanilla enthusiasts.
VirtualBox – Built for the beginner to run a virtual session from ISOs and Discs.
VMware – Built for the professionals to run sessions from numerous sources.

You can downgrade, upgrade, update, or fresh install to meet your multi-boot needs.