The One-Stop Guide to DeDuck

Most computer utilities rush to delete files to show immediate disk space gains. DeDuck is built on the opposite philosophy: evidence before action, and preservation above all else.

Whether you have 20 years of family photos scattered across five external hard drives, dusty USB thumb drives in desk drawers, or complex camera SD cards, DeDuck acts as an impartial auditor and patient curator. It inventories your drives, proves beyond any mathematical doubt which files are duplicates, and helps you organize them into clean rows without ever endangering your precious originals.

Getting started takes less than two minutes. DeDuck is completely portable and requires no account registration, no cloud login, and no background tracking daemons.

DeDuck's Scan tab is much more than a file list. It is an intelligent inventory engine designed to separate your genuine treasures from digital clutter and technical system files.

Modern applications, cameras, and operating systems create hundreds of hidden metadata sidecars and cache files. In inferior tools, these technical files clutter your search or lead to accidental deletion. DeDuck categorizes every file with context-aware precision into 8 distinct categories:

Exploring Your Files: On the right side of the Scan tab, the “All Files” browser lets you search filenames instantly, filter by category pills, switch between List, Icon, and Thumbnail views, and sort by file size or last modified date. Below the main browser, you will find cards displaying your Largest Files, Largest Folders, and Collections.

Every scanned folder card includes a direct “Reveal folder in Finder / Explorer” button so you can instantly open that exact disk path in your operating system with one click.

Two files having the same name does not mean they are duplicates. And two files with completely different names might be 100% identical. DeDuck does not guess; it proves identity through five escalating levels of certainty.

Transparent Keeper Selection & Pre-Library Decision

When duplicates are discovered, DeDuck marks one copy as The Keeper based on your preference (Newest modified, Oldest original, or Shortest file path). The keeper is indicated with a clean badge. You can change the keeper to any other copy with a single click at any time.

Pre-Library Decision: When you decide to build a Master Library from folders containing duplicates, DeDuck offers a clear choice: you can review and clean up duplicates first, or choose “Build Library as-is”. Building as-is automatically de-duplicates files inside the new library copy while leaving your original source folders completely untouched.

Compare is DeDuck's side-by-side reconciliation powerhouse. It is designed for real-world scenarios: comparing a camera SD card against your laptop's photo folder, or checking if Backup Drive B has everything from Drive A.

Additive Reconciliation Modes

When copying files across folders to reconcile them, DeDuck is strictly additive. It never deletes or overwrites existing files. Copies mirror the source folder structure perfectly:

• Make A = B (Two-Way Sync): Copies missing files from B into A, and missing files from A into B. Both sides now contain the union of all files.
• Fill A (A &sup877; B): Copies files present in B that are missing in A across to folder A. Folder B is not altered.
• Fill B (B &sup877; A): Copies files present in A that are missing in B across to folder B. Folder A is not altered.
• Selective Row Copying: Tick individual files in either pane and click “Copy selected →” to copy only chosen items.

Conflict Handling with ~from: If both folders have a file named Notes.txt but their contents are different, DeDuck refuses to overwrite either copy. It preserves the destination file and copies the source file with a safe suffix (e.g., Notes~from_FolderA.txt) so you can review both versions at your leisure.

A DeDuck Master Library (DDL<n>_<name>) is a dedicated, pristine copy of your files, neatly filed and deduplicated. Your original scanned folders are never modified, moved, or deleted.

In DeDuck 1.1.0, the Library tab has been completely redesigned with powerful batch workflows, multi-selection capabilities, and real-time disk synchronization.

Synchronizing Changes Made on Disk (Finder / Explorer)

If you reorganize files, add new photos, or delete files directly inside a Library folder in macOS Finder or Windows Explorer, DeDuck detects the discrepancy. Clicking “Refresh from folder on disk” triggers sync_library_from_disk, which updates DeDuck's database to mirror disk reality without requiring a full rebuild.

Restoring Existing Libraries: If you move to a new computer or reinstall your operating system, click “Restore…” on the Library tab. DeDuck scans your disk for existing DDL folders and re-registers them into your catalog with their full history intact.

Recent Scans Panel: Directly on the Library tab, a Recent Scans section shows your latest cataloged roots with one-click buttons to Rescan, Compare, Create Library, or Safely Remove.

Organizing your files is only half the battle. If your drive crashes tomorrow, organization won't save your memories. DeDuck implements the industry gold-standard 3-2-1 Backup Strategy directly into its workflow.

Symmetrical Source & Destination Architecture

DeDuck features a symmetrical backup setup: you can select any Master Source (a curated DeDuck Library or any scanned folder) and pair it with any Backup Destination (an external volume, network drive, or cloud provider). DeDuck's protection engine audits your entire archive and produces a clear status report showing which files have verified local and offsite coverage, and which files remain at risk.

Modern cloud desktop applications (like Google Drive and OneDrive) use "Files On-Demand" or File Provider placeholders to save local disk space. Unfortunately, this creates severe problems for file management utilities.

In macOS Finder, dataless cloud placeholders often appear as empty files reporting 0 files / 0 Bytes. Standard file cleaners mistakenly report that your folders are empty, or fail completely when trying to verify backups.

The Google Drive Direct API Reconciliation Engine

DeDuck solves this permanently by connecting directly to the Google Drive API using a secure, strictly read-only metadata scope (drive.metadata.readonly). DeDuck bypasses macOS File Provider limitations entirely, querying the authoritative cloud inventory directly.

DeDuck compares your local recovery folder against the cloud inventory using cryptographic MD5 checksums and classifies every file into one of 5 Reconciliation Buckets:

• Already in Cloud: The file is present locally and identical in the cloud. Safe and protected.
• Local Only: The file exists on your local machine but has not yet been uploaded to the cloud. Needs backup!
• Cloud Only: The file exists in your Google Drive cloud archive but is not on your local machine (a dataless placeholder or cloud-only file).
• Conflicts: The file exists in both places under the same path, but the contents or modification timestamps differ.
• MD5 Verified: Cryptographic checksum confirmation that cloud bytes and local bytes match 100%.

Strictly Read-Only Guarantee: Cloud reconciliation never modifies, overwrites, deletes, or uploads files. It provides transparent audit visibility without any risk of accidental cloud alteration.

DeDuck believes in absolute accountability. Every operation performed within the app is recorded in an audit log, and you can generate executive-level shareable reports on demand.

Many users are terrified of duplicate cleaners because one bug can wipe out years of irreplaceable memories. Here is exactly how DeDuck handles file cleanups with absolute mechanical safety:

DeDuck is software you buy once and own forever. There are no monthly subscriptions, no mandatory cloud sync, and no surprise lockouts.

A quick, plain-English reference guide for terms used throughout DeDuck: