Organ Builder by Vincent Forman

Vincent Forman provided the GrandOrgue community with an excellent Windows tool called Organ Builder, which simplifies or assists the creation of organ definition files (ODFs) for the GrandOrgue software. The tool allows the user to easily create playable, basic GrandOrgue ODFs supporting core features, but it does not support advanced GUI creation, effects noises (e.g. drawstop noise), and other advanced features usually showcased in Hauptwerk sample sets.

Unfortunately, the project seems to have been abandoned in late 2014/early 2015 and the website for Organ Builder is defunct. The latest released versions are available below.

Organ Builder Portable

Organ Builder Source