VCV Rack is a free and open-source cross-platform software modular synthesizer.

By default, the software contains several VCOs, LFOs, mixers, and other standard synthesizer modules.

[5][6] Version 1.0.0 added a stable API, a multithreading engine[3] and support for polyphonic signals.

[3] In addition to the above features, VCV Rack can also connect to other hardware and software by outputting analog CV/gate and digital USB or MIDI signals.

The software can also connect to other VST plugins though the module "host".