Helm is a free software synthesizer developed by Matt Tytel. Available format(s): VST, VST3, Audio Unit, LV2 for Windows 64b, macOS.
Helm is a free, cross-platform, polyphonic synthesizer with a flexible modulation system. Helm is open source and you are free to run it anywhere, study and change the source code, and redistribute exact or modified copies of Helm.
http://tytel.org/helm