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.

www.ibrahimshaath.co.uk/keyfinder
github.com/ibsh/is_KeyFinder