Synth1 is described as 'software synthesizer modeled on the Clavia Nord Lead 2 Red Synth. It combines the common sound synthesis method of Subtractive & FM synthesis' and is an app in the Audio & Music category. There are more than 10 alternatives to Synth1 for a variety of platforms, including Windows, Mac, Linux, BSD and iPad. The best alternative is Surge Synthesizer, which is both free and Open Source. Other great apps like Synth1 are Dexed (Free, Open Source), Helm (Free, Open Source), ZynAddSubFX (Freemium, Open Source) and Oxe FM Synth (Free, Open Source).
Dexed is an FM-type softsynth developed by Pascal Gauthier of Digital Suburban. It is an ideal application for importing, playing and editing/managing sysex patches from both the classic Yamaha DX7 synthesizer and the TX7.
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.
A virtual analog synthesizer, Tunefish v4 was developed as a smaller replacement of Tunefish v3 with roughly the same power - some might argue it's even more powerful. It was also ported over to Linux and MacOS and was given a new polished UI.
TAL-NoiseMaker is an improved version of TAL-Elek7ro and has a completely new synth engine and a lot of improvements in sound and usability. The synth also includes a small effect section with a reverb, chorus and a simple bit crusher effect.
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.