Mixed In Key (also known as MIK) is Windows and Macintosh software that simplifies a DJ technique called harmonic mixing. The latest version of Mixed In Key analyzes MP3 and WAV files and determines the musical key of every file. Knowing the key, DJs can use music theory (such as the Circle of Fifths) to play songs in a harmonically-pleasing order. The software helps to eliminate dissonant tones while mixing songs together using a technique such as beatmatching. Mixed In Key software was created by Mixed In Key LLC, a software company based in Washington DC, United States. The company was established in 2006 to release the software to the world-wide DJ audience. Mixed In Key has also spawned a supplementary product, Platinum Notes which corrects audio problems with MP3 and WAV files using iZotope and zplane.development technology. As of December 2006, Mixed In Key LLC became a partner of Allen & Heath, the UK-based company known for its high-end audio mixing consoles.
Mixed In Key software was developed to provide a Windows interface for the tONaRT key detection algorithm created by zplane.development. The original tONaRT algorithm created by zplane.development had a simple Windows-based demo which could not process multiple audio files at once. Yakov Vorobyev created a simple C# .NET Windows application that could batch-process multiple files. The first version was released on March 25th, 2006. Mac OS X development started shortly thereafter, and the first Mac OS X version was released on June 4th, 2006. Since May 2007, Mixed In Key LLC has improved the key detection algorithm by combining tONaRT with a custom in-house algorithm. The new algorithm was released in Version 3.0.