Primer is a synth equipped with the
most essential controls and nothing more. Created by
Audible Genius, it is an exact replica of the synth
used in their flagship synthesizer training app,
For Mac/PC the Standalone version is
available for free as part of the Syntorial Demo (in
the menu select Options->Launch Standalone Synth).
The VST/AU plugin version comes included with the
paid version of Syntorial. The Primer iOS app is
free in the App Store.