puddletag is an audio tag editor (primarily created) for GNU/Linux similar to the Windows program, Mp3tag. Unlike most taggers for GNU/Linux, it uses a spreadsheet-like layout so that all the tags you want to edit by hand are visible and easily editable.
The usual tag editor features are supported like extracting tag information from filenames, renaming files based on their tags by using patterns and basic tag editing.
Then there’re Functions, which can do things like replace text, trim it, do case conversions, etc. Actions can automate repetitive tasks. Doing web lookups using Amazon (including cover art), Discogs (does cover art too!), FreeDB and MusicBrainz is also supported. There’s quite a bit more, but I’ve reached my comma quota.
Supported formats: ID3v1, ID3v2 (mp3), MP4 (mp4, m4a, etc.), VorbisComments (ogg, flac), Musepack (mpc), Monkey’s Audio (.ape) and WavPack (wv).
Keeping an XP partition for Mp3tag just wasn’t feasible anymore.
To Mp3tag it’s not that different. Mp3tag has things puddletag doesn’t have, puddletag has things Mp3tag doesn’t. Skim the menus section to get an overview of the differences.
However, compared to other GNU/Linux taggers the differences are much too vast to list.
puddletag is licensed under the GPLv3, which you can find in its entirety at http://www.gnu.org/licenses/gpl-3.0.html.