A simple but functional drum sequencer created with AI in about 30 minutes, available both as a web-based application (deprecated, not being updated) and a full-featured VST3 plugin (updated as time permits). Inspired by the classic TR-808 but not attempting to replicate the original. Features a pragmatic VST-style interface with comprehensive functionality. Use it freely in your projects!
This project demonstrates the SDD (Spec-Driven Development) approach - a methodology for rapid development using AI agents with structured prompts and templates. For more details on SDD, check out SDDRush.
All prompts used in this project are available in both locations - the SDDRush repo and the sdd directory within this project.
- 12 synthesized drum voices (BD, SD, LT, MT, HT, RS, CP, CH, OH, CY, RD, CB) with Web Audio API synthesis
- 16-step sequencer grid for each voice with visual step highlighting
- Professional VST-style UI with dark theme and gradient panels
- Individual voice mixer with level controls for each instrument
- Parameter controls for per-voice customization (level, tone, decay, tuning, etc.)
- Default atmospheric UK garage pattern pre-loaded
- Adjustable tempo (60-240 BPM) with swing control
- Pattern saving/loading via browser storage
- Real-time step highlighting during playback
- Theme toggle (light/dark mode)
- Keyboard shortcuts support for efficient operation
- Responsive design optimized for desktop and tablet
- Full-featured VST3 instrument compatible with DAWs like Ableton Live, Logic Pro, Reaper
- 12 synthesized drum voices matching the web version
- 97 parameters with full automation support (73 voice + 24 FX sends)
- 36 factory presets across 6 genres (UK Garage, DnB, Techno, House, Trap, Lo-Fi)
- Per-voice FX sends to reverb and delay buses
- Master dynamics chain (compressor, limiter, soft clipper)
- MIDI input support (GM drum map compatible)
- Host sync with tempo and playback state
- Resizable UI (1100x720 - 1650x1080) with HiDPI support
- Accessibility features (keyboard navigation, screen reader support)
- Professional dark theme with custom knobs and faders
- Low-latency audio processing with optimized DSP
- Follows VST3 UI Best Practices 2025 (APVTS, throttled repaints, no OpenGL)
# Install dependencies
npm install
# Start development server
npm run dev
# Build for production
npm run build# Build the plugin (requires CMake and JUCE)
cd native/vst3/CR717
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --config Release
# Copy the resulting .vst3 bundle to your DAW's plugin directory:
# macOS: ~/Library/Audio/Plug-Ins/VST3/
# Windows: Program Files\Common Files\VST3\
# Linux: ~/.vst3/Alternatively, you can use the automated build and install script:
./build-and-install-vst.shThis script will automatically build the plugin and install it to the correct system directory for your platform (macOS, Linux, or Windows).
- Space: Play/Stop
- +/-: Increase/Decrease BPM by 5
- T: Toggle theme (light/dark)
- D: Load default pattern
- ?: Show help
- Escape: Close help
- 1-5: Select voice
- Enter: Toggle step
- Arrow keys: Navigate steps
- Pattern Bank: Switch between 8 preset patterns (A-H)
- MIDI Input: Trigger sounds via connected MIDI keyboard/controller
- DAW Transport: Sync with host DAW playback and tempo
- Parameter Automation: All parameters support DAW automation
- Individual Voice Controls: Custom knobs for level, tune, decay, tone per voice
Web Application: TypeScript frontend with Web Audio API, built with Vite 6, tested with Vitest 4 + Playwright, linted with ESLint + Prettier. Native VST3 Plugin: JUCE 7 framework with CMake build system, Steinberg VST3 SDK for audio, optimized C++ synthesis algorithms.
The web app features centralized state management, precise audio timing with <2ms jitter, modular UI components, and CSS-based design system. The VST3 plugin offers real-time safe DSP, APVTS parameter system for automation, full MIDI support, and sample-accurate host integration. Both platforms deliver efficient performance: the web app has <10 KB bundle size with <2ms timing accuracy, while the VST3 plugin provides low-latency processing with optimized CPU usage. The plugin requires CMake 3.22+ and JUCE to build, supporting cross-platform development via submodules.
- CMake (3.22 or later)
- JUCE (included as submodule)
- Steinberg VST3 SDK (for validation)
- Build tools: Xcode/macOS, Visual Studio/Windows, or GCC/Linux
- Clone the repository with submodules:
git clone --recursive - For web app: use standard npm workflow
- For VST3: use CMake to build native plugin from
native/vst3/CR717/
MIT