MusicBrainz Picard is a cross-platform music tagger.

Features:

Multiple Formats

Picard supports all popular music formats, including MP3, FLAC, OGG, M4A, WMA, WAV, and more.

AcoustID

Picard uses AcoustID audio fingerprints, allowing files to be identified by the actual music, even if they have no metadata.

CD Lookups

Picard can lookup entire music CDs with a click.

Open Source

Picard is licensed under GPL 2.0 or later, and is hosted on GitHub where it’s actively developed by some awesome developers.

Plugin Support

If you need a particular feature, you can choose from a selection of available plugins or write your own.