Getting Started with Deduper

Welcome to Deduper. This guide will help you quickly find and remove duplicate files to reclaim valuable space on your drive.

Deduper uses a unique two-step process—first by size, then by content—to ensure 100% accuracy before you delete anything.

1. Select Your Folder

When you launch the app, click the Select Disc button. You can choose your local hard drive, an external USB drive, or even Cloud Storage folders (like Dropbox, Google Drive, or OneDrive).

Note on Cloud Drives: This works as long as you have the cloud service's desktop app installed and the folder is accessible via Finder (macOS), File Explorer (Windows), or your Linux File Manager (e.g., Nautilus or Dolphin).

First Run

Deduper will perform a full scan of the directory. Please be patient—this process can vary in speed depending on disk performance, internet bandwidth, or even just how cooperative your cloud storage provider is feeling today.

Subsequent Runs

Deduper uses Smart Caching. If you scan the same folder again, the results will load almost instantly!

Tip: If you have freed up a lot of space in the directory while the app was open, click Re-Scan to force a fresh look at the directory.

2. The Candidate View (Grouped by Size)

Once the scan finishes, you will see a list of file groups.

In the vast majority of cases, files of the exact same size are duplicates—even if they have different filenames. While there is a slim possibility that two different files could share the exact same size, the chance is fairly low.

This is where your sharp eyes and hunter reflexes come in. You can often identify obvious duplicates right here, delete them, and free up your disk space immediately.

But sometimes, you need more clarity to make a decision. Simply select a file in any group you need more information about and click Analyze.

Tip: All files in that group will be analyzed—because, after all, we are hunting duplicates. Computing digital signatures takes a lot of processing power. Good thing you have a powerful computer doing it for you!

3. Verify & Delete (Grouped by Content)

After clicking "Analyze," Deduper reads the digital fingerprint (Hash) of the files to see if they are truly identical.

Review: You will now see the Exact Duplicates view. Identical files are marked by a dot located to the left, between the file-name and the selection checkbox. If there is no dot—which rarely happens—then the file is not a duplicate.
Select: Highlight the copies you want to remove.
Delete: Click Delete Selected.

Where do deleted files go?

Deduper moves files to your system Trash. They are not permanently erased until you empty your Trash bin, giving you a safety net if you change your mind.

Frequently Asked Questions

Why do I have to click "Analyze"?

Scanning a massive hard drive for exact content matches takes a long time. By showing you "Size Matches" first, Deduper lets you ignore file sizes you don't care about and only spends computer power analyzing the files you suspect are duplicates.

Can I stop a scan in progress?

Yes. If a scan is taking too long, simply click the Cancel button. Deduper will stop scanning and show you whatever results it found up to that point.

I deleted a file, and the app took me back to the previous screen. Why?

Once you delete a set of duplicates, that specific group doesn't have any duplicates so it's not a candidate. Deduper automatically updates its memory and returns you to the main Candidate List so you can tackle the next group of files.