The 2.9 version of MidiKey for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus.
The software lies within Audio & Video Tools, more precisely Music Production. The most popular versions among the program users are 2.4 and 2.1. You can execute MidiKey on Mac OS X 10.6 or later. This Mac app is an intellectual property of Supertintin.
From the developer:
MidiKey is a cute program that can make your mac keyboard become an instrument keyboard. you can play 128 instruments on your Mac.it is able to receive MIDI input from MIDI keyboard. also can send MIDI OUT to native applications such as GarageBand, Logic Pro, Pd...
You may want to check out more Mac applications, such as Mixtikl 5, Noatikl 2 - Generative Music Lab or VDMX, which might be related to MidiKey.