GRUB - Multiboot boot loader
Libreboot - Libreboot is a distribution of ...
EasyUEFI - Manage EFI/UEFI Boot Options & Manage EFI System Partitions & Fix EFI/UEFI Boot Issues
EasyBCD - EasyBCD is NeoSmart Technologies multiple award-winning answer to tweaking Windows bootloader.
Bootice - Download Bootice - Edit your computer's MBR and PBR settings with various built-in tools such as a partition manager, UEFI editor, BCD configurator, and more
Grub2Win - Safely dual boot Windows and Linux without touching the Windows MBR.