Checked September 2026
DISTRHO
Cardinal review
SynthsFree version
A free, open-source modular synthesizer plugin based on VCV Rack. Best for modular patching inside a DAW. Price: Free.
Key features
- 1,382 built-in modules from 84 authors
- Main, Synth and FX plugin variants
- LV2 with real CV ports
- Open source
- Standalone app included
Pros
- Huge module library
- Free and open source
Cons
- Modular patching has a steep learning curve
Cardinal alternatives
Free spectral warping wavetable synth, the best-known free Serum alternative.
VST3supportedAUsupportedAAXnot supportedCLAPsupportedWINsupportedMACsupportedLNXsupportedFree, open-source hybrid synthesizer with extensive filters and a flexible modulation engine.
VST3supportedAUsupportedAAXnot supportedCLAPsupportedWINsupportedMACsupportedLNXsupported- FREE
Digital Suburban
Dexed
Free, open-source FM synthesizer plugin modeled closely on the Yamaha DX7.
VST3not supportedAUsupportedAAXnot supportedCLAPnot supportedWINsupportedMACsupportedLNXsupported
Sources: cardinal.kx.studio