The Safe, Instant Folder Merge Utility for Mac.
Consolidate divergent backups, external hard drives, and photo archives without fear of accidental overwrites. Instant zero-space cloning with one-click undo.
Built specifically for photographers, creators, and data hoarders.
Designed from the ground up for macOS Sequoia and Sonoma, with zero web runtime bloat.
APFS Zero-Space Cloning
Utilizes Darwin copyfile CoW technology. Merge gigabytes of data on the same APFS volume in milliseconds without consuming double disk space.
Never Overwrite Blindly
Source directory is strictly read-only. Before overwriting any existing file in the destination, a snapshot backup is automatically archived for instant ⌘Z rollback.
Target-Newer Conflict Guard
Smart timestamp inspection detects newer files in the destination directory and skips them by default, safeguarding your latest edits against stale overwrites.
External Drive Protective Scanning
DirMerge never spins up your external USB mechanical hard drives until you explicitly click Start. Zero unexpected throttling or drive thrashing.
100% Offline & Private
Pure macOS App Sandbox compliant. DirMerge requests zero network entitlements. Your filenames, paths, and data strictly never leave your Mac.
Display Scaling & Dock Drag
Comfortable font size tiers (100%, 115%, 130%) with ⌘+ / ⌘- shortcuts for Studio Display & 4K/5K. Drag folders straight onto the Dock icon to launch.
Instant Direction Swapping
Need to sync changes both ways? Press ⌘[ to instantly swap Source and Target directories without re-navigating file pickers.
Lightweight Boutique Tool
Only 2.4 MB Universal binary. Starts in 0.08 seconds and consumes less than 25 MB of RAM. No Electron, no WebKit, pure Swift 6 & SwiftUI.
- Smart Ignore Rules EngineBuilt-in toggles for .DS_Store, .git, node_modules, and custom wildcard patterns (*.tmp, build/) to keep merges clean.
- CLI Helper & URL SchemeInstant terminal invocation via 'dirmerge <dirA> <dirB>' and deep system link support ('dirmerge://').
- Homebrew Cask DistributionOne-command automated deployment and updates via 'brew install --cask zhenqiang-sun/tap/dirmerge'.
- Target-Newer Overwrite ProtectionAutomatic smart timestamp inspection detects and skips newer destination files by default to prevent regressions.
How APFS Zero-Space Cloning Works
Conventional copy utilities waste gigabytes of disk space and write cycles. DirMerge changes the game.
Instant cloning without byte duplication
When copying files within Apple File System (APFS) volumes, traditional tools read source blocks and write duplicate blocks to the destination, doubling physical storage and wearing out SSD cells.
DirMerge invokes Darwin's native copyfile(..., COPYFILE_CLONE). The operating system creates a new namespace entry pointing to the original disk extents.
- ✓ 100 GB folder merged in < 0.1 seconds
- ✓ Consumes 0 additional bytes of physical disk storage
- ✓ Zero SSD write wear until a file copy is subsequently altered
Why choose DirMerge over alternatives?
See how DirMerge compares against macOS Finder, terminal scripts, and legacy tools.
| Feature / Metric | DirMerge 2.0 | macOS Finder | Terminal (rsync) | Beyond Compare | FreeFileSync |
|---|---|---|---|---|---|
| Native macOS Interface | ✓ SwiftUI Native | ✓ System | CLI Only | Qt Port | wxWidgets |
| APFS Zero-Space Cloning | ✓ Automatic (CoW) | Manual Duplicate | ✕ (Full Writes) | ✕ (Full Writes) | ✕ (Full Writes) |
| Read-Only Source Lock | ✓ 100% Enforced | ✕ (Accidental Move) | Script Dependent | Configurable | Configurable |
| One-Click Undo (⌘Z) | ✓ Snapshot Rollback | Unreliable Across Folders | ✕ Irreversible | Manual Backup | Recycle Bin |
| Target-Newer Protection | ✓ Auto-Detect & Skip | ✕ Blind Overwrite | Requires --update flag | Configurable | Configurable |
| Drive Protective Scanning | ✓ On-Demand Only | Auto-Indexes Drive | Immediate Access | Immediate Access | Immediate Access |
| App Sandbox Privacy | ✓ 100% Offline | System Native | Unsandboxed | Network Enabled | Network Enabled |
| Binary Size & RAM | 1.3 MB (<25 MB RAM) | System Default | ~500 KB | ~80 MB | ~50 MB |
| Pricing Model | Free (25 files) / $9.99 Lifetime | Free (Included) | Free (Open Source) | $35 – $70 | Donation / Ads |
3 Simple Steps to Perfect Synchronization
No complex rules, no cryptic regex, no code diff distractions.
Drop Folders
Select or drag your reference folder (e.g. external SSD backup) and your destination folder. Press ⌘[ to swap directions anytime.
Review Differences
Click Start to view real-time breakdown of new, conflict, and identical files with instant live search and filtering.
One-Click Safe Merge
Merge everything in seconds. If you ever change your mind, press ⌘Z to restore overwritten items instantly.
Frequently Asked Questions
Clear answers to common questions about safety, cloning, and storage compatibility.
Does DirMerge overwrite or delete files in my source folder?
Never. The Source directory is mounted and accessed strictly in read-only mode. DirMerge will never delete, move, or modify any file inside your reference folder.
How does APFS Zero-Space Cloning save disk space?
On Apple APFS drives, DirMerge creates Copy-on-Write references rather than copying raw bits. A 50 GB photo shoot or video archive clones in milliseconds while consuming 0 bytes of extra disk space.
What happens if a conflict occurs with an existing file?
Before replacing any conflicting file in your Target directory, DirMerge creates a safe rollback snapshot. If you made an error, click Undo (or press ⌘Z) to restore every replaced item.
Does DirMerge support external drives formatted with exFAT or FAT32?
Yes. While zero-space cloning requires APFS, DirMerge seamlessly supports exFAT, FAT32, and HFS+ volumes with high-speed buffered streaming and complete snapshot protection.
Is DirMerge completely offline?
Yes. DirMerge operates inside the official Apple App Sandbox without network entitlements. It contains no analytics, no telemetry, and zero network calls. Your files never leave your computer.
What is included in the Free version vs Pro?
The free version allows you to merge up to 25 items per batch with full APFS cloning. The Pro Lifetime purchase ($9.99 USD) unlocks unlimited batch merging across all your Mac computers permanently.
How does Target-Newer Protection prevent data loss?
DirMerge inspects file modification dates before merging. If a file in the destination folder is newer than the source, DirMerge badges it with a warning and automatically excludes it from the batch by default, preventing accidental overwrites of your latest edits.
How do I redeem an official Offer Code (e.g. DIRMERGEVIP2026)?
Open DirMerge, click Unlock Pro, and click Redeem Offer Code in the paywall window to redeem your code directly through the official Apple App Store system.