Yate

Yate is for the person whose music lives on a drive rather than in a streaming account, and who has noticed that the same artist is filed under three spellings, half the classical recordings credit the conductor as the artist, and about four hundred albums have no cover. It reads and writes tags across the formats that actually turn up in a ripped or downloaded library, checks releases against MusicBrainz, Discogs and last.fm, and can identify a mystery file by its acoustic fingerprint when the tags are simply absent.

The part that justifies the $20 is Actions: small scripted routines you assemble once — normalise this field, strip that junk, pull artwork at a sane size — and then run across thousands of files unattended. The licence does not expire, updates are included with no version wall, and one purchase activates two Macs at a time, which is the only real limit on it.

If your library is a few hundred tracks bought from one store, the Music app's own Get Info will do, and Yate's window will look like a spreadsheet you did not ask for. It is also not a player or a library manager: it fixes the files, and leaves playing them to something else.