Plex, Navidrome, and Roon read the tag and move on. Music Library Doctor reads the audio — and catches what they can't see.
Plex, Navidrome, Roon, and Subsonic are excellent media servers. They scan your music folder, parse tags, and serve up a beautiful library. What they don't do is verify whether the file is what the tag claims. A FLAC made from a 128 kbps MP3 source plays back through Roon at "lossless" indicators with the same UI weight as a real 24-bit/96 kHz studio master. Duplicates across formats look like separate albums. There's no library-wide quality audit, no fake-flac detection, no way to systematically clean things up — because that's not what a media server is built to do.
Supported today
Rekordbox · Serato DJ · VirtualDJ (incl. Favorite Folders) on Windows 10+ and macOS (Apple Silicon + Intel).
Media servers are file-readers, not file-auditors. MLD fills the gap. The acoustic fingerprint scan finds duplicates your media server's tag-based dedup can't see — like a Hi-Res FLAC and a 320 kbps MP3 of the same recording, sitting in different album folders. The FFT-based quality scorer catches the fake-FLACs that Roon's signal-path UI happily labels lossless. And because MLD operates on the file system directly, your media server doesn't need any plugin or integration — clean up the files, the server rescans, you're done. *Smart Upgrade is a Pro feature; you are responsible for ensuring you have rights to obtain replacement content.*
No, and that's by design. MLD operates on the file system layer. You clean up the files, your media server rescans on its own schedule (or you trigger a manual rescan), and the library updates. No API integration, no plugin to maintain, no auth dance.
Yes. FLAC is a container; the FFT analysis works on the decoded audio, which retains the spectrum cliff of the original lossy source. A FLAC made from a 128 kbps MP3 has the same spectrum signature as the original MP3 — MLD scores it accordingly and flags it.
MLD never re-encodes or transcodes your audio. The only modifying operations are: move to Trash (deletion, reversible), move to a different folder (consolidation), or Smart Upgrade swap (Pro feature — replaces a file with a cleaner version you obtain). All other operations are read-only analysis.
Yes, as long as the folder is mounted on the machine where MLD runs (SMB, AFP, NFS, etc.). Scan speed depends on network speed, but functionality is identical to a local drive.
No. All analysis, fingerprinting, and scoring runs locally. The only outgoing connection is for Smart Upgrade source search (Pro feature) and license validation.
Same answer as Plex/Navidrome/Roon — MLD operates on the file system, so any media server that scans a music folder benefits. Clean the files; the server picks up the changes on its next scan.
Free tier covers detection and viewing. Lifetime access is $49 — $19 for the first 100 DJs.
