VCV Rack is described as 'modular synthesizer inspired by Eurorack systems. It acts a host for virtual modules which perform various audio processes. E.G. oscillators, filters, envelope generators, sequencers and more that can be connected freely in almost limitless combinations'. There are more than 10 alternatives to VCV Rack for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Android. The best alternative is Pure Data, which is both free and Open Source. Other great apps like VCV Rack are SunVox (Freemium), SuperCollider (Free, Open Source), Reaktor (Freemium) and Max/MSP (Paid).
Multiphonics CV-1 is a powerful platform for assembling and playing patches. With a simple and straightforward interface, Multiphonics is a fast and efficient creation tool for musicians and sound designers. It is also a great learning environment for newcomers.
I wanted to build a music creation tool that is easy to use, accessible and free. Zupiter is a synthesizer and step-sequencer that runs in a browser, meaning you don't even need to download and install any software to use it.