DiskScope

A fast, free disk space analyzer for Windows and macOS, written in Rust.

Scan a drive or folder and see where the space went: a cushion-shaded treemap in the spirit of WinDirStat, plus which applications own it, where the large clusters are, and what is safe to delete.

• Fast. Parallel, async scanning; multi-million-file drives in seconds, with the UI staying responsive throughout.
• Understands your system. Attributes space to installed applications and games, not just folders.
• Cleans up carefully. Graded suggestions (Safe / Review / Caution), Recycle Bin or Trash by default, and nothing is removed without a confirmation.
• Small and local. A single executable. No installer, no telemetry, no network access.

• Screenshots · Install · Usage · Deleting files · macOS notes
• Build from source · Contributing · Architecture
• Performance · Known limitations · License

Which app owns the space	What is safe to delete

All screenshots show a made-up demo disk (invented applications and paths), not a real machine.

Download the latest build from the Releases page.

Each release includes SHA256SUMS.txt so you can verify your download.

Intel Macs: the universal app contains an Intel (x86_64) build, and CI checks that it compiles, but it has not been tested on real Intel hardware. It has been run on Apple Silicon. If you try it on an Intel Mac, please open an issue with how it went.

1. Pick a drive from the drop-down, type a path, or press Browse…, then press Scan.
2. Explore with the tabs on the left (Folders, Applications, Clusters, Cleanup, Duplicates, Types, Large files). The treemap on the right follows your selection.
3. Switch Color by between file type, application and cleanup risk to see the same data three ways.
4. In Cleanup, tick what you want to remove and press Delete…. See Deleting files.

Size on disk (on by default) reports allocated space, which is what deleting actually frees. Turn it off for logical file sizes.

A headless report, handy for scripting and benchmarking:

diskscope --cli C:\             # Windows: types, applications, clusters, cleanup suggestions
diskscope --cli ~               # macOS: scan the home folder
diskscope --cli C:\ --logical   # logical file length instead of size on disk

DISKSCOPE_IO_THREADS overrides the size of the I/O thread pool.

Nothing is deleted without a confirmation dialog.

• Deletion goes to the Recycle Bin (Windows) or Trash (macOS) by default. Windows may delete items that are too large for the bin permanently.
• An opt-in checkbox deletes permanently, with a warning. Permanent deletion cannot be undone.
• The scan root and Caution (system-managed) items are refused, and items nested inside another selected item are dropped from the plan.
• Items are removed one at a time, the views update as they go, a progress bar with a Stop button shows in the status bar, and a failure on one item does not stop the rest.

First launch. The app is ad-hoc signed but not notarized (that needs a paid Apple Developer account), so Gatekeeper blocks it the first time: right-click DiskScope.app → Open → Open, or run xattr -dr com.apple.quarantine DiskScope.app once.

Full Disk Access. To scan protected folders (Mail, Messages, Photos, other users' data), grant the app Full Disk Access in System Settings → Privacy & Security. Without it those folders show as unreadable and everything else still works.

Scanning /. Other mounted volumes and the firmlinked Data volume are skipped so files are not counted twice.

Cleanup → Manage simulator runtimes lists Xcode's installed runtime images and their sizes, even when scanning only your home folder. Select Remove…, then confirm permanent removal. DiskScope runs xcrun simctl runtime delete <UUID> in the background and shows any failure from Apple's tool. This skips the Trash and may shut down simulators using the runtime. Refresh the list or rescan afterwards. System-wide CoreSimulator caches are Caution entries rather than ordinary deletion suggestions.

Individual simulator device folders under ~/Library/Developer/CoreSimulator/Devices are listed separately, also as Caution, rather than suggesting deletion of all CoreSimulator data. Use xcrun simctl list devices to identify a device, then xcrun simctl delete <UUID> to remove it and its data. Remove runtime versions through Xcode → Settings → Components. Simulator caches are listed on their own. Rescan after removing a device or runtime to update sizes.

You need a recent stable Rust toolchain. On Windows use the MSVC toolchain.

git clone <this repository>
cd diskscope
cargo run --release     # start the GUI

Contributions are welcome: bug reports, rules for the cleanup engine, platform fixes, and code. See CONTRIBUTING.md for the details. For anything bigger than a small fix, please open an issue first so we can agree on the approach.

Before you send a change

cargo test --locked     # all tests, no window needed

CI runs the tests and a release build on Windows and macOS when a push to main changes Cargo.toml, Cargo.lock or src/.

Good bug reports include your OS and version, what you scanned (and roughly how large), what you expected, and what happened. If a cleanup suggestion was wrong, include the path and the reason DiskScope gave: those rules are easy to improve.

Adding or changing cleanup rules. Portable rules live in src/cleanup.rs; OS-specific ones in src/platform/windows.rs and src/platform/macos.rs. Rules match on a normalised path (lower-case, / separators) so they are written once. Each rule should say why the item is safe, and anything that might lose user data must be Review, not Safe. Add a test with a small synthetic folder tree (see src/tests_platform.rs).

Screenshots and social images. They are generated from a fictional demo disk so no real paths appear: docs/demo/make-demo-disk.ps1 builds it (sparse files, almost no real disk space), diskscope --shot out.png C:demo cleanup --logical --color cleanup captures the GUI, and docs/social/render.ps1 renders the social cards.

Working on macOS code without a Mac. The macOS rules are ordinary unit tests and run on any OS. To check that the whole program compiles for macOS from Windows or Linux:

rustup target add aarch64-apple-darwin x86_64-apple-darwin
# blake3 compiles a little C; a stub compiler is enough for `check` (nothing is linked)
CC_aarch64_apple_darwin=true AR_aarch64_apple_darwin=true \
  cargo check --target aarch64-apple-darwin --all-targets

The program is split along seams so each part can be tested without the others, and without a window. Domain terms are defined in CONTEXT.md.

Measured on a 3.7 million file, ~870 GiB NTFS drive: about 21 s for a warm scan (about 90 s the first time, when the disk cache is cold), ~280 MiB of memory for 4.5 million entries, and a treemap render of roughly 70 ms. Treemap and analysis time scale with the number of items, not with the size of the window.

On a machine with antivirus or EDR, most scan time goes to opening directories through file-system filter drivers, so adding threads stops helping beyond about 8. Reading the NTFS MFT directly would avoid that but needs administrator rights; it is not implemented. Nothing has been measured on macOS yet.

• Intel Macs are untested (see Install).
• macOS has no uninstall-leftover detection yet: there is no reliable installed-app list to compare ~/Library folders against. iCloud "dataless" placeholders are counted as zero bytes, but there is no further iCloud-aware sizing.
• Hard links are counted once per link. Symlinks and junctions are skipped.
• File names are stored as lossy UTF-8.
• Application attribution is heuristic and will sometimes show odd entries.

DiskScope is released under the MIT License.