MX4 is compatible with the Mac OSX OS. It runs within MAS compatible apps like DP, AU compatible apps like Logic and Live and RTAS compatible apps like Pro Tools and Pro Tools LE. As of this writing it is not compatible with VST apps. VST based sequencer users (Cubase, Nuendo) may want to consider using a program like Rax by Granted software to run the AU version of MX4 alongside their sequencer.