At first glance, harmonic mixing software Mixed In Key appears to be a tool for DJs, but a bit of exploration reveals a stunningly clever piece of software.
Using sophisticated algorithms, Mixed In Key analyses your music collection and marks each track with its respective musical key

The key can either be expressed traditionally (‘G Major’, ‘D Minor’ etc) or as a code based on the Camelot Wheel, which requires no musical knowledge.

Once you have flagged the tracks in your music collection with their keys, you can put together groups of songs that are perfectly in tune with each other, an exercise that can often reveal surprising musical bedfellows.

All in all, Mixed In Key works extremely well. The key detection is almost perfectly accurate and the speed at which it flags your files is very impressive. The software works on PC or Mac and costs $58

www.mixedinkey.comy