Kruud is a free synthesizer instrument for Windows.
Kruud VSTI is a synthesizer with a drawable low resolution Oscillator.
The main Osc has 5 basic waveforms , Pink and white Noise and a drawable user waveform. The waveforms have different modes like Phase Mod, PWM (Square only) and a special morph mode (listed as PWM in the synth) for all but the square wave. The user waveform can mi, or morph between two waveforms.