danzig

A VST3 plugin framework in pure Zig. No JUCE, no Steinberg SDK, no C++ in the core. src/vst3.zig implements the VST3 C ABI directly as extern structs of callconv(.c) function pointers, which is what a C++ vtable is at the machine level.

Read the guide: docs/WIKI.md

Setup

git clone https://github.com/godofecht/danzig
cd danzig
./setup.sh

setup.sh checks your Zig version, builds, runs the tests, packages the universal VST3 bundle, and prints where it landed. It exits non-zero on failure and is safe to run repeatedly. Pass --release for a ReleaseFast build.

By hand:

zig build                     # Build Summary: 29/29 steps succeeded
zig build test --summary all  # Build Summary: 9/9 steps succeeded; 35/35 tests passed
zig build vst3                # universal arm64 + x86_64 bundle in zig-out/
zig build install-vst3        # copy it to ~/Library/Audio/Plug-Ins/VST3/

Then:

lipo -info zig-out/DanzigGain.vst3/Contents/MacOS/DanzigGain

Architectures in the fat file: zig-out/DanzigGain.vst3/Contents/MacOS/DanzigGain are: x86_64 arm64

Requirements

• Zig 0.14.1 or 0.15.2. Both are tested in CI on every push.
• macOS for the VST3 bundle, install-vst3, and the GUI example. The library, the unit tests, and the CLI examples are portable Zig.
• Xcode command line tools, for lipo and the macOS SDK.

What's here

Core library (src/)

File	Contents
vst3.zig	The VST3 C ABI: IUnknown, IPluginBase, IComponent, IAudioProcessor, IEditController, and the structs they pass.
plugin.zig	Plugin lifecycle and a heap-backed ParameterMap.
audio.zig	dBToLinear, GainProcessor, SimpleRamp, AudioBuffer.
params.zig	Lock-free AtomicParam and ParamStore(N). One cache line per parameter, no heap, no locks.
tests.zig	35 unit tests.

Examples (examples/)

Example	Run it
danzig-minimal. The smallest complete plugin, and the file to copy.	zig build run-minimal
danzig-gain. The plugin packaged into the .vst3 bundle.	zig build vst3
danzig-test. Drives the built plugin through the raw VST3 C ABI.	zig build test-integration
danzig-gain-standalone. Offline WAV gain processing.	zig build run-standalone
danzig-webui. An HTTP server in pure std.net.	./zig-out/bin/danzig-webui
danzig-gain-ui. Native macOS window, WebView plus CoreAudio.	zig build run-gui

See examples/README.md for the index.

Build artifacts

zig build installs:

zig-out/
├── bin/
│   ├── danzig-minimal              offline demo of the minimal plugin
│   ├── danzig-gain-standalone      WAV gain processor
│   ├── danzig-webui                HTTP server for the web UI
│   ├── danzig-gain-ui              native window (macOS)
│   └── danzig_test                 VST3 ABI integration harness
└── lib/
    ├── libDanzigGain.dylib         gain plugin, native arch
    ├── libDanzigGain_arm64.dylib   gain plugin, arm64
    ├── libDanzigGain_x86.dylib     gain plugin, x86_64
    └── libDanzigMinimal.dylib      minimal plugin, native arch

zig build vst3 adds the bundle:

zig-out/DanzigGain.vst3/
└── Contents/
    ├── Info.plist
    ├── PkgInfo
    └── MacOS/
        └── DanzigGain              universal arm64 + x86_64

libdanzig.a is not installed. The static library is linked into each target rather than shipped on its own.

Sizes, from zig build -Doptimize=ReleaseFast:

Artifact	Size
DanzigGain.vst3/Contents/MacOS/DanzigGain	84 KB (universal)
lib/libDanzigGain.dylib	52 KB
lib/libDanzigMinimal.dylib	52 KB
bin/danzig-minimal	168 KB
bin/danzig-gain-standalone	288 KB
bin/danzig-gain-ui	572 KB

The default Debug build produces the same artifacts at roughly 1 to 2 MB each.

Current state

The core library, the tests, the build pipeline, the examples, and the VST3 plugin all work. examples/danzig-gain builds a universal .vst3 bundle that a host loads and instantiates, and it passes pluginval at strictness level 5:

pluginval --validate zig-out/DanzigGain.vst3 --strictness-level 5
Num plugins found: 1
Testing plugin: VST3-Danzig Gain
...
SUCCESS

The factory returns a populated PClassInfo, and createInstance builds one object exposing IComponent, IAudioProcessor, and IEditController over a shared lock-free parameter store. See Current state for the detail.

Documentation

• docs/WIKI.md. The single-page guide. Architecture, quickstart, parameters, audio helpers, bundle packaging, testing, troubleshooting.
• docs/INDEX.md. The older multi-page docs.

License

MIT. See LICENSE.

VST is a trademark of Steinberg Media Technologies GmbH. danzig vendors no Steinberg SDK code, and shipping plugins in VST3 format is governed by Steinberg's own terms, independently of danzig's MIT license.