SpareDisk Help

Short, plain answers to the questions the interface raises: what the numbers mean, why some items cannot be moved, and what the Trash frees. The same text is available inside the app under Help.

Sizes

Logical size

What a file would hold if it were fully downloaded and uncompressed. Finder shows this number in Get Info as the first figure.

Size on disk

The space a file actually occupies right now. Cloud files that are not downloaded, sparse disk images and cloned copies take far less than their logical size. SpareDisk shows an on-disk hint whenever a file occupies less than half its size. The View menu and Settings switch every list, map and total to sizes on disk.

Why totals differ

The volume bar counts everything on the disk. A location counts only what is inside it. System files, other users, snapshots and folders you have not added as locations make up the rest. Hard links are counted once, as du does.

Locations and permissions

What a location is

A folder you granted SpareDisk access to. Your home folder covers Desktop, Documents, Downloads and Library in one step. Applications and external drives are separate locations. Several folders can be added at once and scan one after another.

Why macOS asks

macOS confirms once before an app reads a protected folder such as Desktop or Downloads. SpareDisk never asks for Full Disk Access and cannot read outside the folders you add.

Forgetting a location

Forget Location in the sidebar removes the saved permission and the saved scans for that folder. Nothing on disk changes.

Review and the Trash

Review first

Add to Review stages items in a queue. Nothing moves until you confirm. Move to Trash in the inspector does the same for one item, or for every selected item, with a confirmation.

Checked again

Before an item moves, SpareDisk checks that it is still the same file: same identity, size and date, still inside the location. Anything that changed is skipped and listed with the reason.

What the Trash frees

Moving to the Trash frees nothing by itself. Space returns when you empty the Trash in Finder. Cloned files and files with several hard links may free less than their size.

Items SpareDisk cannot move

Apps and files owned by the system or another user need an administrator password, which only Finder can ask for. Cloud files that are not downloaded are managed in Finder as well. SpareDisk says so on the item and offers Finder.

Duplicates

How they are found

Among the largest files of each scanned location, files of the same size are sampled at the start, middle and end, hashed with SHA-256, then compared byte by byte. Only identical contents are grouped. Progress is shown by bytes read.

Keeping one copy

Each group keeps one copy. Stage the Rest for Review stages the others; the kept copy is never moved by group actions, and cleanup refuses the last copy of any group.

Identical is not the same

Two identical files can mean different things to different apps. Check where each copy lives before removing it.

Related data for apps

What Find looks for

Containers, group containers, caches, preferences, saved state, logs and Application Support that match the app's bundle identifier under your Library, plus vendor folders such as Google/Chrome. Matches by name only are marked as weaker evidence. Each item is scanned for its real size.

What it does not do

SpareDisk does not uninstall apps or stop background helpers. Items go through the same review and Trash flow as everything else, and nothing is preselected.

Comparing scans

SpareDisk keeps the previous completed scan of each location. The location's bar shows the change since then, and clicking it lists the top-level folders and files that grew, shrank, were added or were removed. Unreadable folders are reported as unreadable, not as removed.

Keyboard

• ⌘O add a location. ⌘R rescan the current location. ⌘I show or hide the inspector.
• Space Quick Look. Return open or expand a folder. Arrow keys move between map cells.
• ⌘⇧R add the selection to Review. ⌘⌫ move the selection to the Trash after confirmation.
• ⌘[ and ⌘] go back and forward. ⌘? open Help.

Privacy

Everything stays on this Mac

Scanning reads names, sizes and dates. Duplicate comparison reads file contents to hash them. Nothing is uploaded and there is no account.

What is stored

The last two scans per location and your saved folder permissions live in the app's own container. Forget Location removes them. See the privacy policy.