Duplicates: find identical files and keep one of each

How it compares files

Duplicates works from your latest scan, so start by scanning your home folder or any folder. Click Find Duplicates and MacClearings compares files in three passes:

1. Files of the same size are grouped. Everything else is set aside.
2. Within each group, the first and last 64 KB are compared.
3. Files that still match are hashed with SHA-256, the whole file, so only identical contents remain.

Comparing only reads. By default it looks at files of 1 MB or more; Settings → Cleanup can lower that to 100 KB or raise it to 100 MB. Apps, libraries and system files are never included: Duplicates skips app data in Library, the insides of apps and packages like a Photos library, symbolic links, and cloud files that haven't been downloaded.

In the screenshot, Duplicates found 2,425 groups holding 17.3 GB of extra copies if one of each is kept. The first group is a 28.8 MB file with 16 copies across different project folders.

Choosing what to keep

The menu at the top sets the rule for every group at once:

• Keep Newest keeps the most recently modified copy and selects the rest.
• Keep Oldest does the opposite.
• Keep Copies in Folder… asks for a folder and keeps the copy inside it. Groups with no copy in that folder fall back to keeping the newest.

Each group lists every copy with its path and modification date. The copy being kept is marked Keep. Tick or untick any copy to change it, and use the eye button to open Quick Look. If you try to select the last copy in a group, MacClearings stops you: "One copy always stays. Select another copy to keep first."

Copies inside build, .build, DerivedData, .next and .gradle folders are tagged Build output. In the screenshot, two copies of a 393 MB Flutter library sit in the build folders of two projects. Building either project again makes it again. If you work with build folders often, the project build artifacts rule in Suggestions handles whole folders instead of single files.

Why clones and hard links aren't duplicates

On an APFS disk, copying a file can make a clone: a second file that shares the same storage until one of them changes. A hard link is a second name for the same file. In both cases, the extra copy takes almost no space, so moving it to the Trash would free nothing. Duplicates checks for both and leaves them out. Hard links are also counted once in the Map, so its sizes stay honest.

From selection to the Trash

The footer shows what's selected, for example "3,822 copies selected · 17.3 GB", and whether those copies are in the Cleanup tray yet. Add to Cleanup stages them. Review & Clean Up… stages them and opens the review list in one step. Nothing moves until you confirm.

When you choose Move to Trash, MacClearings checks once more that at least one copy of every file stays. If every copy of a file got into the tray some other way, say one from Find and the rest from here, it unstages one and tells you. Each copy is also checked for changes since it was measured, and skipped if it's open in an app.

The copies go to the Trash, and every cleanup can be undone from History while they're still there. The space comes back when you empty the Trash yourself. The safety page explains each check.

Photos and other libraries

The insides of a Photos, Music or iMovie library are left out, and MacClearings never picks those libraries apart. For photos, use the Duplicates album in the Photos app, which merges copies inside the library the way Photos expects.