Voltage Modular is a free VST/AU virtual “modular case” for macOS and Windows compatible with most DAWs. It also runs as a Stand-Alone soft-synth.

Developers can freely design and publish modules with the equally free Voltage Modular Designer, and there’s a bunch of both free and paid modules available from a range of DYI as well as more established vendors.

If you already own the Ignite bundle, you can upgrade to the Core bundle for a reduced price, and gain over 70 new modules.