Dunno of any, but the CLI tools TMSU, Tocc, and Tagistant all create their own file systems (using symlinks) inside your drive's existing one that can then be accessed by other software. Pretty handy.

• Calibre
  Digital book manager with good metadata editing tools.
• EasyTAG
  Gnu tool for tagging audio files. Never tried.
• ExifTool
• Ex Falso
• MediaElch
• MediaInfo
• Musicbrainz Picard
• pdftag
• tinyMediaManager
• VLC
  Lets you edit a small set.

Software that stores it's own database of tags, as a way to consistently tag all sorts of files, no matter what metadata they support. I've tried some before for organising images and videos, and am currently trying some for organising music samples and sound effects.

• Baloo Homepage
  KDE tool with a limited CLI sister-tool.
• Hydrus Network Homepage
  Channer affiliated :/
• TagFlow Homepage
  Roadmap talks a lot about cloud stuff…
• Tagistant Homepage
  CLI, TSMU seems better though.
• TagSpaces Homepage
  Open-source, but free version is limited :/
• TMSU https://tmsu.org/
  CLI tool.
• Tocc Homepage
• Tracker Homepage
  Gnome thing

• Tag Manager
• NEPOMUK (software)

I generally just use these tags:

• TIT2 ／ title
• TPE1 ／ artist
• TALB ／ album
• TPE2 ／ albumartist - Quod Libet labels this performer. Usually only use if there are multiple artists, software seems to sort stuff right otherwise.
• TYER ／ date
• TPOS ／ discnumber - If there are multiple.
• TCON ／ genre - I have set genres I use, and I also place the country and sometimes city in here.
• TRCK ／ tracknumber
• COMM ／ comment - If I want to specify it's a Youtube rip or something.

Ones that seem neat that I should use:

• TSST ／ discsubtitle
• TLAN ／ language - Fill with three-letter language code from ISO-639-2
  • List of ISO 639-2 codes
  • NB: mul for multiple, zxx for none.
• TSOP ／ artistsort
• TSO2 ／ albumartistsort - Starting to try these two 'sort' tags now though.
• TSOT ／ titlesort
• TSOA ／ albumsort
• Multiple ones for artist-related URLs - https://wiki.hydrogenaud.io/index.php?title=Tag_Mapping#URLs.
  • WOAF ／ ? - Track website.
  • WOAR ／ ? - Track artist website. Well supported across file types.
  • WOAS ／ ? - Source website.

Maybe notable ones I don't bother with are:

• TCOM ／ composer
• TSOC ／ composersortorder
• MVIN ／ movementnumber
• Shit like play counts and ratings. Though considering a use for ratings.

• https://wiki.hydrogenaud.io/index.php?title=Tag_Mapping