If you want to easily tag multiple MP3, Ogg/Vorbis, FLAC, MPC, MP4/AAC, MP2, Opus, Speex, TrueAudio, WavPack, WMA, WAV and AIFF files (e.g. full albums) without typing the same information again and again and have control over both ID3v1 and ID3v2 tags, then Kid3 is the program you are looking for.
KeyFinder is an open source key detection tool, for DJs interested in harmonic and tonal mixing. It’s intended to be very focused: no library management, no track suggestions, no media player. Just a fast, efficient workflow tool. It supports a huge range of codecs thanks to LibAV, and writes to metadata tags using TagLib.