MusicDNS provides a simple web service to identify digital music tracks and provide basic metadata. Using the approved open-source-licensed Open Fingerprint Architecture (libofa) SDK — or commercial licenses from AmpliFIND — any Internet-connected computer can query the MusicDNS web service. The Portable Unique IDentifier (PUID) that's returned will identify the master recording, regardless of digital format. The track metadata returned by MusicDNS can be used freely for any application needs.
Note: MusicDNS is being discontinued and their servers are far from dependable right now.
m3lib Cache File Format