SyncDrop

OneDrive for your own hardware — auto-sync the folders you choose to any drive you plug in, the moment it connects.

SyncDrop is a lightweight macOS menu-bar app. No dock icon, no window clutter.

Think of it like OneDrive or iCloud Drive — but instead of syncing to a cloud you don't control, it syncs the folders you pick to your own storage device. Configure your folders once; then whenever you connect the configured drive — an external SSD, USB pen drive, or hard disk — SyncDrop automatically mirrors your selected files onto it. Plug in, it syncs, you're backed up. No subscriptions, no cloud, your data stays yours.

Plug in your drive → SyncDrop detects it → mirrors your folders → done.

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Install

Option A — Download the app (recommended)

1. Download SyncDrop.zip from the latest release.

2. Unzip it (double-click) and drag SyncDrop.app into your /Applications folder.

3. First launch. Double-click it. macOS shows "Apple could not verify SyncDrop is free of malware." That's expected — the app isn't notarized yet (see below). To open it:

   On macOS 15 (Sequoia) and later:

   1. Click Done on the dialog.
   2. Open → System Settings → Privacy & Security.
   3. Scroll down to the message "SyncDrop was blocked…" and click Open Anyway.
   4. Authenticate, then click Open. Done — you only do this once.

   On macOS 13–14 (Ventura/Sonoma): right-click SyncDrop.app → Open → Open.

   Or, from Terminal (any version): one command, then just double-click normally:

   xattr -dr com.apple.quarantine /Applications/SyncDrop.app

4. The SyncDrop icon appears in your menu bar. Click it → Settings to set up.

Why the warning? SyncDrop is open-source and code-signed, but not yet notarized by Apple — notarization requires a paid Apple Developer account ($99/yr). The build is safe and fully auditable here; you can also build it yourself in one command. Notarization is on the roadmap.

Option B — Build from source

Requires the Swift toolchain (Xcode or Command Line Tools).

git clone https://github.com/abhinay-hat/SyncDrop.git
cd SyncDrop

make app        # builds a signed SyncDrop.app in the repo root
make install    # builds and copies it to ~/Applications

Other targets:

swift build     # debug build
swift test      # run unit tests (needs full Xcode, not just Command Line Tools)
make clean      # remove build artifacts

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First-time setup

Open the menu-bar icon → Settings, then in the Folders tab:

1. Source (Mac) — choose the folder you want backed up (e.g. ~/Desktop/Projects).
2. SSD Volume Name — type the exact name of your SSD as it appears in Finder (e.g. Extreme Pro).
3. Destination (on SSD) — plug in the SSD, then choose the target folder on it.

In the Behavior tab, turn on Auto-sync when SSD connected if you want it to run automatically. That's it — plug in the drive and SyncDrop syncs.

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Features

Feature	What it does
Auto-sync on connect	Plug in your SSD and the sync starts (opt-in per profile).
Multiple profiles	Different source/destination/exclude sets, switchable from the menu.
Dry-run preview	See exactly what will be added, updated, or deleted before committing.
Mirror mode	Adds --delete so the SSD exactly matches the Mac.
Versioned backups	Overwritten/deleted files are kept under .syncdrop_archive/<date> instead of discarded.
Exclude patterns	rsync glob patterns, with sane macOS defaults (.DS_Store, node_modules, …).
Auto-eject	Safely ejects the SSD after a successful sync.
Sync history & notifications	Recent runs (files, size, duration) and a completion notification.
exFAT-safe	Avoids permission/ownership flags that break on exFAT; uses --modify-window=1 for its 2-second timestamp granularity.

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Requirements

• macOS 13 (Ventura) or later
• rsync — ships with macOS at /usr/bin/rsync
• (Source builds only) Swift toolchain

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How it works

VolumeMonitor watches NSWorkspace mount/unmount notifications and matches your configured SSD volume name. On connect — with auto-sync enabled — SyncEngine launches rsync with a per-profile argument list, streams progress from stdout, and reports state through Combine to the menu-bar UI. Profiles, settings, and history persist in UserDefaults via ConfigStore.

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Project layout

Sources/
  SyncDropCore/    # rsync engine, volume monitor, config, models (no UI)
  SyncDrop/        # AppKit + SwiftUI menu-bar app
Tests/             # XCTest unit tests for the core
android/           # Android port (work in progress)
Resources/         # app icon (.svg source + .icns)

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Roadmap

SyncDrop today is macOS → local drive. The goal is sync the folders you choose to any storage you own, from any device. Planned:

• NAS / network drives — sync to a NAS or any mounted network share, not just USB-attached drives.
• Android app — sync from your phone to a USB-OTG SSD/pen drive (in progress under android/).
• Windows app — the same plug-in-and-sync experience on Windows.
• More targets — any drive type macOS/Windows can mount (SSD, pen drive, HDD, SD card).

Have a use case or want to help build one of these? Open an issue.

Android (in progress)

An Android port (Kotlin + Jetpack Compose) targeting USB-OTG drive sync is in early development under android/.

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Contributing

Issues and pull requests welcome. Build with make app, run swift test before submitting.

Releasing (maintainers)

make app        # ad-hoc signed bundle, hardened runtime (notarization-ready)
make zip        # clean, AppleDouble-free SyncDrop.zip for distribution

To ship a notarized build (no Gatekeeper warning for users), you need a paid Apple Developer account, then:

export APP_IDENTITY="Developer ID Application: Your Name (TEAMID)"
export APP_STORE_CONNECT_KEY_ID=...        # App Store Connect API key id
export APP_STORE_CONNECT_ISSUER_ID=...     # issuer id
export APP_STORE_CONNECT_API_KEY_P8="$(cat AuthKey_XXXX.p8)"
make notarize   # builds, signs with Developer ID, notarizes, staples, zips

See Scripts/sign-and-notarize.sh.

Automated releases (GitHub Actions)

Pushing a v* tag triggers .github/workflows/release.yml, which builds, packages, and attaches SyncDrop.zip to a GitHub Release:

git tag v1.0.1 && git push origin v1.0.1

If these repo secrets are set, the workflow signs with Developer ID and notarizes; otherwise it falls back to a clean ad-hoc build (still uploaded):

Secret	What
APP_IDENTITY	Developer ID Application: Your Name (TEAMID)
MACOS_CERTIFICATE_P12_BASE64	Developer ID cert exported as .p12, base64-encoded
MACOS_CERTIFICATE_PASSWORD	password for that .p12
APP_STORE_CONNECT_KEY_ID	App Store Connect API key id
APP_STORE_CONNECT_ISSUER_ID	issuer id
APP_STORE_CONNECT_API_KEY_P8	contents of the AuthKey_XXXX.p8

License

MIT © 2026 Abhinay Reddy