Does anyone know any free alternatives to Informator?
As a sidenote, this doesn't deal with EXIF metadata only. I'm hoping for video, music, and who knows what else beside images metadata. Being able to view and edit as well.
Unfortunately there do not see to be any tools which let you edit the Apple metadata beyond the standards created for digital images like EXIF, which I understand you aren't concerned about.
You can achieve the writing of metadata elements such as
Example for writing the file's origin:
See more here