Tech-Stack

Toolchain

Node.js >= 23 (runtime & package manager)
Vite 7.x (dev server & build)
Vitest 3.x (unit tests)
TypeScript 5.x
Sass
ESLint + @typescript-eslint + eslint-config-prettier
Prettier
Turbo (incremental tasks)
Lerna (workspace orchestration)
Rust >= 1.82 with the wasm32-unknown-unknown target, a nightly toolchain for the device crates and Binaryen wasm-opt (audio engine)

Monorepo

The repository is a multi-package workspace managed with npm workspaces, Turbo, and Lerna:

Shared TypeScript config via @opendaw/typescript-config
Consistent linting via @opendaw/eslint-config
CI-friendly caching and parallel builds via Turbo
Rust crates in crates/ form a Cargo workspace that is built into @opendaw/studio-core-wasm

Apps

app-studio (the studio at opendaw.studio)
app-manual (this manual, a small standalone app without the audio engine)
app-lab (experiments)

Audio Engine

The audio engine is written in Rust and compiled to WebAssembly. It runs inside an AudioWorklet for real-time playback and inside a Web Worker for offline rendering (exports, freeze). Samples are written straight into the engine's memory, so audio data is never copied between JavaScript and the engine.

engine is the host module. It owns the linear memory and a shared function table.
Every device (instruments, audio and MIDI effects, currently 30 crates in crates/stock-devices/) is compiled as its own position-independent side module and linked into the running engine at load time, so devices can be added without rebuilding the host.
engine-env is the small standard library the devices are written against, abi the contract between host and devices, boxgraph and studio-boxes mirror the box graph on the Rust side, dsp, math, transport, value and voicing hold the shared DSP, timing, automation and voice management, signalsmith and stretch provide time stretching.
Modules are optimised with wasm-opt. Scriptable devices (Werkstatt, Apparat, Spielwerk) run user scripts inside the engine.

The earlier TypeScript engine (studio-core-processors) is still shipped as a fallback.

Libraries

openDAW uses minimal external dependencies, avoiding hidden behaviors from bulky UI frameworks.

Each in-house library has a clear, focused purpose.

In-House Runtime

lib-std (Core utilities, Option/UUID/Observable)
lib-dsp (DSP & Sequencing)
lib-runtime (Runtime utilities, scheduling, network helpers)
lib-dom (DOM Integration)
lib-jsx (JSX Integration)
lib-box (Runtime Immutable Data Graph)
lib-box-forge (Box SourceCode Generator)
lib-fusion (Composition utilities)
lib-midi (MIDI utilities)
lib-xml (XML IO)
lib-dawproject (DAWproject app agnostic IO)
lib-inference (Neural network inference via ONNX Runtime, e.g. stem separation)
studio-enums (Shared enumerations and colors)
studio-boxes (Predefined boxes)
studio-forge-boxes (Box generators)
studio-adapters (Adapters for audio/sample/media)
studio-core (Core studio domain)
studio-core-processors (TypeScript AudioWorklet processors)
studio-core-wasm (Rust/WebAssembly engine, worklet and offline worker glue)
studio-core-workers (Web Workers)
studio-p2p (Peer-to-peer project and sample exchange)
studio-scripting (Scripting runtime and the generated scripting API docs)
studio-icons, studio-markdown, studio-scrollbars (UI pieces shared by the studio and the manual)
studio-sdk (Meta package for SDK distribution)

Dependency Table

Library	Dependencies
lib-std	none
lib-dsp	std
lib-runtime	std
lib-dom	std, runtime
lib-jsx	std, dom
lib-box	std, runtime
lib-box-forge	std, dom, runtime, box
lib-fusion	std, dom, runtime, box
lib-midi	std, dsp
lib-xml	std
lib-dawproject	dsp, runtime, xml
lib-inference	std, runtime, fusion
studio-enums	std
studio-boxes	std, box, enums
studio-forge-boxes	std, runtime, box, dsp, enums
studio-adapters	std, runtime, box, dsp, fusion, boxes, enums
studio-core	std, runtime, box, dom, dsp, fusion, dawproject, adapters, boxes, enums
studio-core-processors	std, runtime, box, dsp, adapters, boxes, enums
studio-core-workers	std, runtime, box, dsp, adapters, boxes, enums
studio-scripting	std, runtime, box, dsp, adapters, boxes, enums
studio-core-wasm	std, runtime, box, dsp, fusion, adapters, boxes, core
studio-p2p	std, runtime, dsp, adapters
studio-icons	std, dom, jsx, enums
studio-markdown	std, dom, jsx, runtime, enums, icons
studio-scrollbars	std, dom, jsx, runtime

External

jszip (Pack & Unpack Zip-Files)
markdown-it + markdown-it-table (Markdown parsing/rendering)
monaco-editor (Code editor for scripting)
mediabunny (Video export via WebCodecs)
d3-force + force-graph (Graph/layout)
dropbox (Cloud storage integration)
yjs + y-websocket (Real-time collaboration)
zod (Schema validation)
soundfont2 (Soundfont parsing)
@ffmpeg/ffmpeg (Audio/Video processing)
onnxruntime-web (Neural network inference)
@opendaw/nam-wasm (Neural Amp Modeler for the Tone3000 device)
ts-morph (TypeScript AST for code generation)
TypeDoc (Scripting API reference)