DiskManager — free disk space analyzer for macOS

Find out what's taking up space on your Mac. DiskManager scans your whole drive in seconds, draws it as an interactive sunburst and treemap, and lets you delete what you don't need — including the ~70% of your disk that Finder refuses to show you.

Free, open source, native Swift. No subscription, no upsell, no paywalled delete button.

---

Why another Mac disk space analyzer?

Because Finder cannot answer the question. It hides ~/Library, hides every dot-folder, shows no folder sizes without Get Info on each one, and cannot rank files by size.

On the machine this was built for, that adds up to 230 GB of 330 GB used being invisible:

Location	Size	Visible in Finder?
~/.cache (Hugging Face, uv, pip)	67 GB	❌ dot-folder
~/Library	110 GB	❌ hidden by default
~/.npm, .gradle, .ollama, .android	46 GB	❌ dot-folders
/opt (Homebrew)	17 GB	❌

Features

• Sunburst and treemap — see your whole disk at a glance, drill into any folder, switch views without losing your place.
• Biggest files — every large file on the volume in one ranked list.
• Hidden — opens directly on ~/Library and your dot-folders.
• Dev Junk — finds node_modules, Gradle, npm, uv, pip caches, Xcode DerivedData, Hugging Face and Ollama model weights, Android emulators, Docker images. Each one says what deleting it actually costs you.
• Duplicate finder — byte-identical files, grouped, oldest copy marked.
• Search — by name, size, or "untouched for two years".
• Move and copy across volumes, with real progress on large files.
• Safe deletion — everything goes to the Trash by default. System and SIP-protected paths are refused outright.
• Space accounting — explains the gap between what it found and what macOS reports, instead of leaving it a mystery.

Download

Grab the latest .dmg from Releases, open it, and drag the app to Applications.

First launch

The app is ad-hoc signed and not notarized (notarization needs a paid Apple Developer account). macOS will refuse the first launch. Either:

• right-click the app → Open, then confirm, or
• run:

xattr -dr com.apple.quarantine /Applications/DiskManager.app

You only need to do this once.

Full Disk Access

Grant it under System Settings → Privacy & Security → Full Disk Access, then rescan. Without it macOS silently reports protected folders as empty, so your totals will be wrong rather than merely incomplete. The app detects this and tells you instead of quietly under-reporting.

Requirements

• macOS 14 (Sonoma) or later
• Apple Silicon (arm64)

How it compares

	DiskManager	DaisyDisk	GrandPerspective	OmniDiskSweeper	WhatSize
Price	Free	$9.99–29.95	Free / $2.99	Free	$14.99
Visual map	Sunburst + treemap	Sunburst	Treemap	❌ none	Chart
Delete from app	✅	✅	✅	✅	✅
Duplicate finder	✅	❌	❌	❌	✅
Developer cache rules	✅	❌	❌	❌	❌
Hidden-space view	✅	❌	❌	❌	❌
Explains unaccounted space	✅	❌	❌	❌	❌

Performance

Measured on a 460 GB Mac with 3.93M files:

Full volume scan	14.9 s (376–419% CPU)
Peak memory	445 MB
Accuracy vs du -skx	exact — 289,789,825,024 bytes, both
Developer junk found	173 GB
Duplicates found	49.4 GB across 1,326 sets, in 20.6 s

FAQ

What is "System Data" on my Mac and why is it so large?

It isn't one folder. macOS lumps caches, logs, swap and APFS snapshots into that label, and they live all over the disk. DiskManager shows you the actual folders instead of a category, and reports snapshots and purgeable space separately.

Why does my Mac say a file is 460 GB when my disk is smaller?

Sparse files. Docker.raw claims 494 GB while occupying 19 GB — the rest was never written. Analyzers that trust the apparent size report a single file bigger than the whole disk. DiskManager measures allocated blocks and shows the apparent size only to explain the difference.

Is it safe to delete node_modules, ~/.gradle, or ~/.cache?

Mostly yes, and the app tells you which. It separates caches that rebuild from what's already on disk (node_modules → npm install) from ones that re-download gigabytes (Hugging Face weights) from things that are genuinely irreplaceable (Android emulator images, Docker volumes).

Does it delete anything without asking?

No. Items are staged in a tray with a running total, confirmed once, and moved to the Trash. Permanent deletion exists but sits behind a menu and a typed confirmation. System and SIP-protected paths are never removed.

Is it a free DaisyDisk alternative?

That's the intent. DaisyDisk is a good-looking paid app with no duplicate finder, no developer-cache rules, and no hidden-space view. GrandPerspective is free but its interface dates to 2005. This aims to be free and modern and able to delete.

---

Build from source

No Xcode required — Command Line Tools are enough.

git clone https://github.com/ashwinn-si/diskManager.git
cd diskManager
./Scripts/run.sh

Script	What it does
Scripts/run.sh	debug build → .app → launch
Scripts/bundle.sh	release build → ad-hoc signed DiskManager.app
Scripts/dmg.sh	icon → release bundle → DiskManager.dmg
Scripts/test.sh	full test suite (76 tests)
Scripts/make-icon.swift	regenerates Resources/AppIcon.icns

Scripts/test.sh exists because swift-testing ships inside Command Line Tools but SwiftPM doesn't add its framework path when Xcode is absent. Plain swift test fails with no such module 'Testing'.

Command line

The scan engine has its own entry point, so it can be measured against du without launching the app:

swift run -c release ScanCLI / --top 20      # largest files on the volume
swift run -c release ScanCLI ~ --junk        # developer caches and build output
swift run -c release ScanCLI ~ --dupes       # byte-identical files
swift run -c release ScanCLI / --account     # space accounting vs. the OS
swift run -c release ScanCLI --volumes       # mounted volumes and capacity

How it works

getattrlistbulk(2) returns ~1000 directory entries per syscall with sizes, inode numbers and flags attached — versus one stat per file. Work is spread over real threads, not Tasks, which would block Swift's cooperative pool on the frontier's condition variable.

The tree is parallel arrays, not objects: ~39 bytes per node with interned names, so 3.9M nodes fit in a few hundred megabytes with no refcounting. Every parent sits at a lower index than its children, which makes subtree rollup a single reverse pass with no recursion.

Hard links are charged once, by inode. Symlinks and mount points aren't followed. Unreadable folders are recorded rather than skipped silently, which is what lets the accounting panel name the gap instead of leaving it unexplained.

The reconciliation reports a signed gap. A scan can find less than the volume holds (unreadable folders, sealed snapshots) or more (APFS clones share storage but carry a full allocation against every name), and the two need different words.

Duplicate detection funnels rather than hashing everything: group by size (free — the scan already knows every size), then hash 4 KB from each end, then full SHA-256 on the few that survive. Both hashing stages run across threads.

The app is not sandboxed, because App Sandbox forbids the whole-disk enumeration it exists to do.

Project layout

Sources/
  ScanKit/           engine — no UI, unit-tested, benchmarkable on its own
    BulkEnumerator   getattrlistbulk wrapper and record parser
    ScanEngine       threaded walk, work queue, shared accumulation
    NodeStore        struct-of-arrays tree + rollup
    SunburstLayout   wedges, culling, polar hit-testing
    TreemapLayout    squarified, nested layout
    JunkRules        developer cache rules
    HiddenSpace      what Finder will not show
    DuplicateFinder  size → head/tail hash → full SHA-256, in parallel
    Search           name/size/age filtering over the interned name blob
    Trash            deletion rules, Trash round trip, permanent delete
    Transfer         move/copy via copyfile(3), progress, conflict resolution
    Reconciler       space accounting, snapshots, Full Disk Access probe
  ScanCLI/           terminal harness
  DiskManagerUI/     SwiftUI views
  DiskManagerApp/    @main entry

Licence

Free to use.

---

_{Keywords: mac disk space analyzer, macOS storage analyzer, free DaisyDisk alternative, what is taking up space on my Mac, find large files Mac, disk usage visualizer, System Data macOS, clean up Mac storage, sunburst disk map, treemap disk usage, duplicate file finder Mac.}