GRUB
Grub2Win
EasyUEFI
EasyBCD
PLoP Boot Manager
Libreboot
BootIt Bare Metal
Grub Customizer
kdiff3
Beyond Compare
WinMerge
Meld
Araxis Merge
DiffMerge
P4Merge
Devart Code Compare
kdiff3Grub2Win - Safely dual boot Windows and Linux without touching the Windows MBR.
Beyond Compare - Beyond Compare allows you to compare files and folders.
EasyUEFI - Manage EFI/UEFI Boot Options & Manage EFI System Partitions & Fix EFI/UEFI Boot Issues
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
EasyBCD - EasyBCD is NeoSmart Technologies multiple award-winning answer to tweaking Windows bootloader.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.