MusiCards Sync

Support and privacy information

About

MusiCards Sync maintains one trusted music archive and keeps synchronized copies ready for the places where you listen. It treats the music archive you designate as the source of truth, then mirrors it to one or more local or remote destinations — such as a portable SSD, a home server running Navidrome or a car music library. It also creates the library.json index used by MusiCards.

Sync is one-way: each destination is updated to match the source. A destination is a storage location, not a speaker or playback device; another app or system can use the synchronized library there.

System requirements

MusiCards Sync is designed for Apple Silicon Macs and requires macOS 26 or later.

Download for Apple silicon

Download MusiCards Sync 1.0

First setup

1. Choose the source folder that contains your trusted music archive.
2. Add one or more destinations. A local destination can be another folder or an external SSD; a remote destination can be a home server or another SSH-accessible computer.
3. For a remote destination, enter its display name, host, user name, music-folder path and SSH port.
4. Run Sync Preview to see which files and folders would change. Preview does not copy files or rebuild the library index.
5. Choose the sync operation you need and start it.

Sync operations

• Sync rebuilds the library index and synchronizes all configured destinations.
• Sync Without Rebuild uses the existing library index and synchronizes the selected destination or destinations.
• Rebuild Library Index rebuilds library.json in the source library without transferring files.
• Sync Files Only performs file synchronization only and does not create, replace or remove library.json.

Remote sync (SSH)

Remote synchronization uses SSH. During first-time pairing, MusiCards Sync uses your SSH password to install its public key on the destination. The password is not saved. Later connections use the installed key, so switching between saved destinations does not require signing in again.

The app bundles its own rsync executable for local synchronization work. Remote destinations must provide a compatible rsync installation that is available over SSH.

Online-only cloud files

If the source library is stored in a File Provider location such as Dropbox, some files may be online-only. macOS can expose a different local modification date for these dataless placeholders than for the fully downloaded file.

When Sync Preview detects modified files that are still online-only, MusiCards Sync shows a warning. Those files may be downloaded and transferred again even when their contents have not changed. The app does not suppress the transfer or assume that equal file sizes mean equal contents.

If the source library is fully available offline, this File Provider timestamp issue does not apply.

MusicBrainz-ready albums

The synchronization report shows how many album folders contain a MusicBrainz Release MBID. Tag albums with MusicBrainz Picard so MusiCards can match releases and tracks reliably.

Library index

A normal Sync rebuilds the source library.json, removes the previous destination index before changing the destination music library, then publishes the new index after file synchronization has completed and verifies the result. This prevents an outdated index from describing a partly updated library.

Sync Files Only intentionally leaves library.json untouched.

Third-party software

MusiCards Sync includes rsync 3.5.0 and its bundled third-party components. License and attribution texts are available from Third-Party Licenses… inside the app and are also included with the distributed application.

Support

If pairing or synchronization fails, first confirm that the destination is reachable, SSH access is enabled, the destination path exists, and the user has permission to write there. The progress report contains the detailed rsync or SSH error.

If Sync Preview reports unexpected modified files in a Dropbox or other File Provider source, check whether those files are online-only. The warning shown by MusiCards Sync indicates that macOS may be reporting placeholder modification dates rather than the dates visible on a fully downloaded copy.

Removing a saved remote location from MusiCards Sync only removes its saved configuration from the app. It does not delete music or remove the installed SSH key from the destination.

Questions, suggestions and feedback are always welcome.

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Privacy Policy

MusiCards Sync does not require an account and contains no advertising, analytics, tracking or crash-reporting service operated by the developer.

• Source and destination settings are stored locally on your Mac.
• SSH passwords are used only during pairing and are never saved by the app.
• The private SSH key used by MusiCards Sync remains on your Mac. Pairing installs only the corresponding public key on the selected remote destination.
• Music files and the library index are transferred directly between your Mac and the destination you selected. They are not routed through or stored on a developer-operated server.
• MusiCards Sync does not collect your music-library contents, filenames, MusicBrainz metadata, destination details or synchronization history for the developer.
• Previewing online-only files uses filesystem metadata only. MusiCards Sync does not intentionally download or read audio contents merely to determine whether the File Provider warning should be shown.
• Removing a saved remote location from the app does not delete music or SSH keys from the destination.