Around 2017, this program got replaced by a better editor called Quad64
Toad's Tool 64 is a hacking tool that lets you move around objects, add objects, modify objects and even delete objects. It was commonly used with a custom level importer to import levels to add the objects in the custom level.
This program is made using Adobe Director, therefore it works with Windows 98 and superior, but recent versions had problems--it doesn't even open properly in Windows 10 (due to how old the program it was). A workaround was to use the Shockwave version or change compatibility to "Windows 98" in the executable properties, but results may vary to some people.