# DirMerge

> DirMerge is a native macOS boutique utility for aligning and merging folders across local drives and external storage with APFS zero-space cloning and undo protection.

## Core Capabilities
- **APFS Zero-Space Cloning**: Utilizes Darwin `copyfile(..., COPYFILE_CLONE)` Copy-on-Write (CoW) technology. Clones files on the same APFS volume in milliseconds without consuming double disk space.
- **Safe by Default & Reversible**: Source folder is strictly read-only. Target directory overwrites automatically create safe snapshot backups with 1-click ⌘Z undo rollback.
- **External Drive Protective Scanning**: Never spins up USB external hard drives until explicit user initiation.
- **100% Offline & Sandboxed**: Complies with macOS App Sandbox (`com.apple.security.app-sandbox`). Zero network entitlements requested. Absolute user data privacy.
- **Lightweight Native Performance**: Pure Swift 6 + SwiftUI + AppKit. 1.3 MB binary size, 0.08-second cold start, less than 25 MB RAM consumption.

## Specifications
- Operating System: macOS 13.0+ (Ventura, Sonoma, Sequoia)
- Architecture: Universal Binary (Apple Silicon M1/M2/M3/M4 & Intel x86_64)
- Supported File Systems: APFS (Native CoW Clone), HFS+, exFAT, FAT32, NTFS (read-through)
- Pricing: Free for up to 25 items per batch; Pro Lifetime License ($9.99 USD) via StoreKit 2 for unlimited batch processing.
- Multi-language: English, Simplified Chinese, Traditional Chinese, Japanese, Korean, German, French, Spanish, Italian, Portuguese.

## Key Links
- [Official Website](https://dirmerge.com/): Product overview and direct DMG download
- [Support & FAQ](https://dirmerge.com/support.html): Technical details, common questions, and troubleshooting
- [Privacy Policy](https://dirmerge.com/privacy.html): Statement of 100% offline and zero-telemetry architecture
- [Full LLM Documentation](https://dirmerge.com/llms-full.txt): In-depth algorithmic and architectural documentation