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).
Pd (aka Pure Data) is a real-time graphical programming environment for audio, video, and graphical processing. It is the third major branch of the family of patcher programming languages known as Max (Max/FTS, ISPW Max, Max/MSP, jMax, etc.
SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker). It is a tool for those people who like to compose music wherever they are, whenever they wish. On any device.
A real time audio synthesis engine, and an object-oriented programming language specialised for music. SuperCollider was created in 1996 by James McCartney, Since version 3 it is released as free software.
Native Instruments Reaktor is a virtual, modular synthesis platform. REAKTOR also provides a platform for modular synthesis in the form of Blocks – a range of sound generating and sound shaping modules.
Interactive visual programming environment for music, audio, and media In use for over twenty years by performers, composers, artists, scientists, teachers, and students, Max is the way to make your computer do things that reflect your individual ideas and dreams.
Orca is an Esoteric Programming Language and live-coding environment for musical experimentation. In Orca, each letter of the alphabet is an operation, lowercase letters operate on bang, uppercase letters operate each frame.