MainStage is a software developed by Apple Inc. Its primary purpose is to serve as a method of centralizing any virtual instruments that users might have installed on their computers that are normally used in Apple's DAW software Logic Pro for use in live performance.
The instruments can then be played using a pre-recorded MIDI file or via a MIDI controller such as a keyboard. MainStage's other features include the ability to play back pre-recorded backing tracks and to function as a guitar and vocal multi-effects processor.
The second version, MainStage 2, was released on July 23, 2009, along with updated releases of many of the other applications in the Logic Studio package. Since version 2.2, updates are available only from the Mac App Store.
The most recent version, MainStage 3, was released in July 2013 as a paid update.