OpenMacStorage

A free, open-source disk space analyzer for macOS. Maps your filesystem, demystifies the "System Data" bucket, and helps you reclaim space — no subscriptions, no nags, no telemetry.

Think WizTree-meets-CleanMyMac, written in Swift, MIT-licensed.

Install

Grab the latest OpenMacStorage.dmg from the Releases page and drag the app into Applications.

Because the app isn't notarized by Apple's developer programme, macOS will warn you the first time you open it. Either:

1. Right-click → Open in Finder (instead of double-clicking), or
2. After the warning, go to System Settings → Privacy & Security and click Open Anyway.

This is the standard Gatekeeper flow for open-source apps; the source code is right here in this repo if you want to verify it before running.

About this project (a note from the author)

I'm a MacBook user, not a professional developer. I built OpenMacStorage because macOS's storage settings frustrated me — I'd open System Settings, see "Other: 176 GB" with no way to investigate, and the third-party tools that did answer that question all wanted a subscription or kept nagging me to upgrade. The thing I needed didn't exist as free software, so I made it.

The Swift code and architecture were written with significant help from AI (Claude). I drove the product decisions — what features to include, how the UI should feel, which problems were worth solving — and the AI did most of the actual coding under my direction. After using it on my own machine for a while, it felt selfish not to share it. There's nothing here that should be locked behind a paywall.

A note for fellow developers: I know there are mixed feelings in some communities about software built by non-developers using AI assistance. I get it, and I want to be straightforward about it. The code is here for anyone to read, audit, or fork. If you spot bugs, security issues, or just badly written code, please tell me — I'd much rather learn and fix it than ship something broken. PRs that improve the code, the translations, or the features are very welcome.

— Murat (muratkaya665@gmail.com)

Features

• Fast parallel scanner using getattrlistbulk(2) — millions of files in ~60–90 seconds on a modern Mac.
• Sparse-file aware — uses ATTR_FILE_ALLOCSIZE so OrbStack/Docker disk images and dataless iCloud files report their actual on-disk size.
• Treemap visualization with squarified layout, drill-down, breadcrumb.
• Folder browser with multi-select, Quick Look (Space), keyboard shortcuts, and one-click move-to-Trash.
• Search across the scanned tree by name, size, or category.
• Duplicate finder — three-stage hashing (size → 64 KB head-hash → full SHA-1) to skip unnecessary I/O on large trees.
• Old downloads cleaner for ~/Downloads and iCloud Drive.
• App uninstaller — finds an app's Application Support, Caches, Containers, Preferences etc. by name + bundle ID and removes them together.
• "What grew?" — diffs the latest two scans, highlights folders that grew by ≥100 MB.
• File type stats — totals per extension (.mp4, .nsp, .zip…).
• System Data analyzer — Time Machine local snapshots, Xcode DerivedData / iOS DeviceSupport / Simulators, Docker/OrbStack VMs, caches, sleep image.
• One-click cleanup for safe categories with size estimation and confirmation.
• Persistent scans — last scan is saved to disk; opens instantly next time.
• Drag & drop — drop any folder onto the window to scan it.

Languages

Ships with translations for:

• 🇬🇧 English
• 🇹🇷 Türkçe
• 🇨🇳 简体中文 (Simplified Chinese)
• 🇪🇸 Español
• 🇧🇷 Português (Brasil)
• 🇷🇺 Русский
• 🇩🇪 Deutsch
• 🇫🇷 Français
• 🇯🇵 日本語

Translations were AI-seeded for breadth. Native-speaker refinements via PRs are very welcome — see CONTRIBUTING.md.

Requirements

• macOS 14 (Sonoma) or later
• Xcode 16 / Swift 6.0 toolchain to build from source
• Full Disk Access (System Settings → Privacy & Security) to scan inside ~/Library, Mail, Messages, etc.

Build from source

git clone https://github.com/MuratDugan/OpenMacStorage
cd OpenMacStorage
./scripts/make-app.sh           # produces OpenMacStorage.app
open OpenMacStorage.app

# Or build a distributable DMG (requires `brew install create-dmg`):
./scripts/make-dmg.sh           # produces OpenMacStorage.dmg

Or open Package.swift in Xcode and run.

How it's built

• Scanner: getattrlistbulk(2) for one syscall per directory (vs. one per entry with readdir+stat). A worker pool of min(8, CPU count) threads drains a shared queue; sibling directories are scanned in parallel.
• Persistence: Custom binary archive (scan.bin, ~50 MB for a million nodes). Raw little-endian fixed-width integers + UTF-8 strings, recursive pre-order. Loads in ~0.5 s.
• UI: SwiftUI with @Observable for the model, Charts framework for bar graphs, custom squarified treemap, AppKit bridges for Quick Look and trash.
• Localization: Localizable.strings per locale, English keys, falls back cleanly to English for any missing key.

Privacy

OpenMacStorage runs entirely on your Mac. It does not phone home, send analytics, or upload any data anywhere. The only network access is whatever macOS itself does when you open files in Finder via the app's "Show in Finder" buttons.

Roadmap

• App icon + signed/notarized DMG
• External volume scanning (/Volumes/*)
• Optional iCloud "evict local copy" action for cloud-only files
• Pluralization via .stringsdict for nicer count display
• RTL UI polish for Arabic/Hebrew

Disclaimer

OpenMacStorage performs destructive operations (moving files to the Trash, emptying caches, deleting Xcode DerivedData and APFS snapshots, removing app support files). The app asks for confirmation before each destructive action, keeps a confirm-then-trash flow rather than direct deletion where possible, and skips system-critical paths by default — but the responsibility for what gets deleted is yours.

Before using cleanup features, please make sure you have a recent backup (Time Machine or equivalent).

By using this app you accept:

• The software is provided "as is", without warranty of any kind (see LICENSE).
• The author is not liable for any data loss, broken applications, or system issues that may result from using this app.
• This software was built with AI assistance by a non-professional developer. The source code is open for anyone to read or audit.

The same disclaimer is shown in the app on first launch and accessible anytime via Help → Disclaimer & Liability….

License

MIT — do whatever you want with it, no warranty.