DirMerge - Safe Folder Sync

DirMerge is an elegant, native macOS utility created for photographers, developers, creators, and data hoarders who need to consolidate and align divergent folders across local SSDs and external hard drives without the fear of accidental overwrites.

Built from the ground up for macOS Sequoia and Sonoma, DirMerge leverages Apple's native APFS Copy-on-Write (CoW) technology to merge gigabytes of data in milliseconds while consuming ZERO additional bytes of disk storage.

--- WHY CHOOSE DIRMERGE? ---

* APFS ZERO-SPACE CLONING
Traditional copying duplicates raw data blocks, wasting disk space and wearing out SSDs. DirMerge calls Darwin's native copyfile() system API to create instant Copy-on-Write extents. A 50 GB photo shoot or project folder clones in milliseconds with 0 bytes extra storage.

* SAFE BY DEFAULT (STRICT READ-ONLY SOURCE)
Your Source directory is strictly locked as read-only. DirMerge will never delete, move, or modify any file in your reference folder.

* ONE-CLICK UNDO (Command-Z) WITH SNAPSHOT BACKUP
Before replacing any conflicting file in your Target directory, DirMerge archives a safe pre-merge snapshot in a rollback journal. Made a mistake? Press Command-Z to restore everything to its exact pre-merge state.

* EXTERNAL DRIVE PROTECTIVE SCANNING
DirMerge never spins up mechanical USB drives or triggers thermal throttling until you explicitly click Start. Perfect for cold storage, SD cards, and archival hard drives.

* 100% OFFLINE & PRIVACY-FIRST
Built in strict compliance with the official Apple App Sandbox. DirMerge requests ZERO network entitlements. It contains no tracking pixels, no analytics SDKs, and zero telemetry. Your files and filenames never leave your Mac.

* ONE-KEY DIRECTION SWAP
Need to synchronize changes in both directions? Press Command-[ to instantly swap Source and Target folders without navigating file pickers again.

* FEATHERWEIGHT NATIVE SPEED
Pure Swift 6 and SwiftUI. Starts in 0.08 seconds, weighs only 1.3 MB, and consumes less than 25 MB of RAM. Zero Electron or WebKit bloat.

--- HOW IT WORKS IN 3 SIMPLE STEPS ---

1. DROP FOLDERS: Select your reference source folder and target destination.
2. REVIEW DIFFERENCES: Click Start to view a clear categorization of New, Conflicting, and Identical files with live search.
3. SAFE MERGE: Click Merge to consolidate everything instantly with APFS zero-space speed. Undo anytime with Command-Z.

--- SUPPORTED STORAGE FORMATS ---

* APFS (Instant Zero-Space Copy-on-Write Cloning)
* HFS+ (Mac OS Extended)
* exFAT, FAT32, and NTFS (High-speed buffered streaming with snapshot protection)

--- TRANSPARENT PRICING ---

* Free Tier: Enjoy full APFS cloning features for up to 25 items per batch merge.
* Pro Lifetime License ($9.99 USD): Single in-app purchase unlocks unlimited batch processing on all your Macs permanently. No subscriptions.