tuneXplorer is described as 'What do you need to create perfect mix? No matter what method you use - harmonic mixing or beatmatching, you will need to know the basic characteristics of the audio track, such as the key and tempo. tuneXplorer will help you find the key of song and BPM value with high accuracy' and is an app in the Audio & Music category. There are four alternatives to tuneXplorer for Mac, Windows and Online / Web-based. The best alternative is Mixed in Key. It's not free, so if you're looking for a free alternative, you could try Tunebat or KeyFinder.
KeyFinder is an open source key detection tool for DJs who are interested in harmonic and tonal mixing. Designed primarily for electronic and dance music, it is highly configurable and can be applied to many genres.