WhySynth is described as 'versatile softsynth which operates as a plugin for the' and is an app in the Audio & Music category. There are five alternatives to WhySynth for a variety of platforms, including Linux, Windows, Mac, BSD and Advanced Linux Sound Architecture. The best alternative is FluidSynth, which is both free and Open Source. Other great apps like WhySynth are ZynAddSubFX (Freemium, Open Source), yoshimi (Free, Open Source), Phasex (Free, Open Source) and GiMeSpace TouchSpace Synth (Paid).
ZynAddSubFX is a fully featured open source software synthesizer capable of making a countless number of instruments, from some common heard from expensive hardware to interesting sounds that you'll boost to an amazing universe of sounds.
Yoshimi is a software synthesizer for Linux based on the 2.4.0 release of ZynAddSubFX, written by Nasca Octavian Paul. Yoshimi delivers the same synth capabilities, along with very good Jack and Alsa midi/audio functionality.
This program was created to make playing music on a computer more intuitive and affordable for anyone who wants to make music. It offers the most natural way to make music by simply using your touch screen or your hand in front of the web cam.