Cardinal

About

Cardinal is a free and open-source virtual modular synthesizer available as a plugin in AudioUnit, CLAP, LV2, VST2, and VST3 formats, and as a standalone app for FreeBSD, Linux, macOS, Windows, and the Web. It is a DPF-based plugin wrapper around VCV Rack that uses Rack's code directly rather than forking the project, with the goal of providing a fully self-contained, free and open-source plugin version of Rack. Cardinal contains Rack, some third-party modules, and internal utilities in a single binary; its Core modules have been replaced with simplified equivalents suited to audio plugins, and it does not load external modules or connect to the official Rack library or store.

Cardinal is described as stable, with the note that CLAP support is still a work in progress, VST3 plugin hosting inside Carla or Ildaeil is considered experimental, and 32-bit Windows builds still have a few problematic modules. Official builds are available for Linux, macOS, and Windows, with nightly builds available from GitHub for recent commits. The project offers three plugin variants, Main (8 audio and 10 CV ports), Synth, and FX, all with MIDI input and output, plus a Mini variant with a small hand-picked module selection that exists as LV2 and Standalone and supports separating DSP from the UI.