Wii Freeloader (by Datel) is a GameCube-slot disc that patches the video mode in real-time to boot out-of-region GameCube games. It does not modify the Wii's NAND or system software.
Homebrew Channel + Nintendont on any Wii or Wii U (vWii):
Freeloader is safe but obsolete. Softmod + Nintendont is superior in every way.