Mirror: The Alternative to ChronoSync and FreeFileSync
When you wrap a shoot having solid backup of the job is key. For years, professionals on macOS have been stuck choosing between powerful-but-cluttered legacy utilities and cross-platform tools that never quite feel at home on a Mac. I've written about my gripes with Chronosync and preference for FreeFileSync in the past. But I couldn't just leave it at that, I thought there was room for improvement. So I spend the past 4 months making that thought into a reality.
Introducing Mirror:
Mirror was built to end compromises. A native Mac app built from scratch, Mirror is a drag-and-drop file backup utility with one focus: keep your data safe, keep it fast, and stay out of the way. It's the tool I wanted to exist.
Why Mirror?
To understand why Mirror exists, look at the tools most of us have been using. ChronoSync and FreeFileSync each come with trade-offs.
- ChronoSync became an industry standard, but it carries years of legacy complexity. Its two-way syncing can risk overwriting your master data if misconfigured, and the interface shows its age.
- FreeFileSync is incredibly capable, but it's a cross-platform tool. It looks and feels like software designed for another operating system. It gets the job done, but it's not the experience you expect from a Mac app.
Mirror takes the best ideas from both and strips away the friction: an information-rich progress view, a clean native interface, and a relentless focus on data safety.
One-Way by Design
Mirror is strictly a one-way sync engine. It copies from a source folder to one or more destinations, either one at a time or all at once (copying to multiple drives simultaneously is an optional setting, best when each drive has its own connection and not sharing a bus). Because it never writes back to your source, your original data stays completely untouched. Mirror is not about creating bootable backups or snapshots. Its about having one or more mirror copies of your source data.
Your Last Good Backup Is Never at Risk
When Mirror updates a file, it writes the new copy to a hidden temporary file first. The old backup is only replaced after the new copy is fully written and safely on disk. If a drive gets disconnected or your power drops mid-transfer, your previous backup remains intact and you'll never end up with a half-written file where a good copy used to be.
Resumable Transfers
If a large file transfer is interrupted, whether you stop the sync, a drive disconnects, or the app closes, Mirror can pick up where it left off. It checks the partial copy against the original before resuming, so the completed file is always correct.
Pause and Resume
Pause the sync mid-file with ⌘P and resume whenever you're ready. Mirror pauses the actual data transfer, not just the queue, so nothing is wasted.
Real Verification, Without the Wait
After a sync, Mirror can verify every copied file against the source using xxHash-64 checksums. It's a hashing method so fast that your drive speed is the only bottleneck, never the math. You get real confirmation that your copies match the originals, without the long wait that comes with traditional checksums.
Graceful Error Handling
A single locked file or permission error never kills an entire sync. Mirror logs the problem, skips the file, and keeps going. If a drive is ejected mid-sync, Mirror detects it immediately and stops gracefully instead of flooding you with hundreds of write errors. When it's done, every issue is waiting in a clear error log you can export and review.
Feature Comparison
| Feature | Mirror | ChronoSync | FreeFileSync |
|---|---|---|---|
| Interface | Native macOS with real-time progress view | Complex, Legacy UI | Cross-Platform |
| Data Safety | Strict One-Way (Source Never Touched) | Two-way (requires careful setup) | Configurable (requires correct setup) |
| Multiple Destinations | Yes (simultaneous or sequential) | Separate tasks per destination | Yes |
| Pause / Resume | Yes (mid-file, mid-sync) | Limited | Pause only |
| Interrupted Transfer Resume | Yes (picks up large files where they stopped) | Not offered | No (restarts the file) |
| Drive Disconnect Handling | Detects ejection instantly, stops cleanly, resumes later | Varies | Logs per-file errors until the run ends |
| Safe File Replacement | Yes (a good copy is never overwritten until the new one is safe) | Not documented | Temp file copy |
| Post-Sync Verification | xxHash-64, one click (drive-speed fast) | Optional checksum | Optional (hidden setting) |
| Automation | URL scheme (Stream Deck, Shortcuts, Raycast) | AppleScript | Command-line batch jobs |
Comparison based on ChronoSync and FreeFileSync as tested in July 2026. Features in other products may change over time.
Other Features
- Preview Every Sync: Trial Run mode shows every file that will be copied, moved, or removed before committing a single byte. Select a file and press Space to leave it out of the run.
- Smart Archive: Files removed from the source aren't permanently deleted. They're moved to a preserved archive folder on the destination, and you can browse and restore them right in the app, per destination or all at once.
- Two Sync Modes: Mirror makes the destination an exact copy of the source. Backup only adds new and changed files, never removing anything (ideal for archives that only grow).
- Scheduling: Run syncs on timed intervals, at specific times on specific days, or trigger them automatically the moment an external drive is connected.
-
Automation: Control Mirror from Stream Deck,
Shortcuts, Keyboard Maestro, Alfred, or Raycast using simple URLs
(e.g.,
mirror://sync?preset=Backup).
Native, Lightweight
Your files and your sync history never leave your Mac. Mirror has no accounts, no analytics, and no telemetry outside of a quick license check and an optional check for updates, and once activated it works fully offline.
Mirror includes a fully functional 7-day free trial with no restrictions. After that, a one-time license unlocks the app on up to two Macs and includes every 1.x update. No subscriptions, no accounts, no nagging.
