OwlDisk

A fast, open-source disk space analyzer for macOS. Built with Go and Wails.

Features

• Fast parallel scanning — uses 64 concurrent goroutines to scan your disk quickly
• Interactive sunburst visualization — drill down into directories by clicking arcs
• Accurate size reporting — matches macOS Finder and About This Mac figures
• Drag to trash — drop files and folders onto the trash zone to free up space
• Full Disk Access detection — warns you when permissions are limiting scan accuracy
• Universal binary — runs natively on both Apple Silicon and Intel Macs

Screenshots

Disk Selection	Scan Results

Installation

Download

Download the latest .dmg from the Releases page.

Build from Source

Prerequisites:

• Go 1.21+
• Node.js 18+
• Wails CLI v2

# Clone the repo
git clone https://github.com/owldisk/owldisk.git
cd owldisk

# Install dependencies
make setup

# Run in development mode
make dev

# Build the .app bundle
make build

# Build a DMG installer
make dmg

Usage

1. Grant Full Disk Access for accurate results:

   • Open System Settings → Privacy & Security → Full Disk Access
   • Add OwlDisk.app
   • Restart the app

2. Select a disk from the main screen, or choose "Select a folder to scan"

3. Explore the sunburst chart:

   • Each ring represents one level of directory depth (3 levels visible)
   • Arc size is proportional to the folder/file size
   • Click an arc to drill down
   • Click the center circle to go back up

4. Manage files:

   • Drag items from the file list to the trash zone to delete them
   • Click "Reveal" to open the file in Finder

Architecture

owldisk/
├── app.go              # Wails app bindings (scan, trash, finder)
├── main.go             # App entry point and Wails config
├── scanner/
│   ├── scanner.go      # Parallel directory walker
│   ├── diskinfo.go     # Disk enumeration via statfs
│   ├── diskinfo_darwin_cgo.go  # macOS NSURL available capacity (CGO)
│   └── tree.go         # FileNode tree structure and pruning
├── frontend/
│   ├── src/
│   │   ├── App.tsx     # Main disk selection screen
│   │   └── components/
│   │       ├── DiskDetail.tsx    # Scan progress and results view
│   │       ├── SunburstChart.tsx # D3 sunburst visualization
│   │       ├── FileList.tsx      # Navigable file list panel
│   │       └── TrashDrop.tsx     # Drag-to-delete zone
│   └── wailsjs/        # Auto-generated Go bindings for frontend
├── build/
│   ├── appicon.png     # App icon source
│   └── darwin/         # macOS build resources (Info.plist, icon.icns)
└── docs/               # GitHub Pages website (owldisk.com)

How It Works

1. Disk enumeration: Uses statfs + macOS NSURL API (via CGO) to get disk info including purgeable space
2. Parallel scan: Walks the directory tree with 64 concurrent goroutines, collecting file sizes
3. Tree pruning: For quick scans, removes items below 0.05% of total to keep the JSON manageable
4. Visualization: Frontend receives the tree via Wails events and renders it with D3's partition layout

Requirements

• macOS 11.0 (Big Sur) or later
• Full Disk Access recommended for accurate results

License

MIT