Duplicate Detective - User Guide

Last Updated: Jun 16, 2017 08:35AM IST
Duplicate Detective scans your Mac for duplicate files and folders. It then displays a list of matching duplicates, allowing you to easily select those that you wish to delete in order to free up precious disk space on your Mac.
First Launch and Using the App:

When the app launches, you are presented with a first-launch dialog box as follows:

Click on the ‘+’ icon to select a folder to scan for duplicates from the Finder window that appears. Once you have clicked on a folder, click the ‘Choose’ button on the bottom right corner of the Finder window. Alternatively, you can also drag and drop folders directly into Duplicate Detective to perform a scan on them.


Please note: When dragging and dropping folders to scan into Duplicate Detective, ensure you do not drag folders from the Finder sidebar - these include folders such as your Documents folder and other shortcut icons. These Finder sidebar folders are shortcuts, and not folders, and dragging them away from a Finder window deletes that shortcut, regardless of whether you drag it into the app or not.


Once you have selected the folder to be scanned, please click the ‘Start Scan’ button found on the bottom right corner of the app window. The scanning for duplicates shall now commence.

Scanning for Duplicate Files:

As a scan occurs, you will notice a progress bar with status messages informing you that your scan is occurring. A folder containing a large number of files will take considerably more time to scan than a small folder. The progress indication will assure you that the app is still scanning and to kindly remain patient.


Once a scan has occurred, you will notice the total number of files scanned, the number of duplicates found and the storage space taken up by all of the duplicates that were discovered. You can then choose to either go back a step or click ‘Next’ to start deleting these duplicates, as seen below:

Scan Results Deleting Duplicate Files:


Once scanned, you are now presented with the option to individually or collectively delete the duplicate files found. By default, you are presented the ‘All’ file types view. You can sort documents by Folders, Images, Audio, etc from the top black bar. You can also use the search bar to individual locate a particular file or kind of file by name, and further sort search results by Size, Type, Name, Count, and Selected, in ascending or descending order.

Each file can be clicked on, and a Preview of the file is presented in the large right hand side column of the app window. You can click the magnifying glass to be taken to the exact location of this file on your Mac.


Upon making your selections, click the ‘Next’ button to be presented with a final screen showing your selected duplicate files that are marked for deleting. Confirming this will delete this items and send them to your Trash (by default), showing you how much space has been freed up. You can then either Quit the app or Start Again to rescan.

Note: Do not tick all copies of a file for removal unless you wish to totally delete the file from your system. The auto-select button will delete all but one instance of the file (i.e. remove all duplicate copies and just keep the single original version).




When running the app, click on Cmd + , (command and comma) or hit the top left ‘Duplicate Detective’ text from the menubar (next to the Apple logo), to enter the Preferences menu.


In the Preferences menu you can choose toggle between ticking or not ticking files to be deleted to the Trash. By default, when a scan is done and selected files are marked for deletion, Duplicate Detective then deletes them by moving them to the Trash. The Trash can then be emptied out according your needs, or the files can be housed in the Trash. However, by removing the tick from this option, when files are deleted via the app, they are not sent to the Trash and are instead permanently and irreversibly deleted.

You are presented with a few other options that allow for:

i) The ability to create an alias when deleting duplicate files, which when enabled, creates a shortcut pointing to the original file when deleting duplicates.

ii) The ability to auto select the Oldest or the Newest iteration of the duplicate files found.

iii) The ability to set a minimum file size to look for. Duplicate Detective will only scan files that size or larger.

iv) The ability to ignore certain file extensions. We have listed some by default, you can choose to add/delete to this list according to your preferences.

v) The ability to add certain folders listed by you that you do not wish Duplicate Detective to scan through.
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