In Online connect mode, changes to a file are immediately uploaded and in sync when an application has finished saving a file. Files are accessed on demand from the remote when opened and do not take up any local disk space. Files are not synchronized on local disk but only saved temporarily when required and deleted at the latest when the bookmark is disconnected.


You can only access volumes in Online connect mode when a connection is possible to the server or cloud storage.

Status of Files

Files and folders on a mounted volume have a status icon overlay in File Explorer (Windows) and Finder (macOS).

macOS only

Please make sure to enable the Mountain Duck Integration in System Preferences → Extensions → Finder on macOS. For macOS Ventura and later, the setting can be found in System Settings → Privacy & Security → Extensions → Added Extensions.

Online Only

The file can only be opened when a connection to the server or cloud storage can be made. The file does not take any space on your computer. The file is downloaded on demand when you open it.


The file or folder is only saved in a local temporary location and not uploaded. This includes files matching a temporary filename pattern, empty files and new folders.

Transfer progress

While transferring files and folders, a transfer progress window shows in or Windows Explorer. When completed, the file(s) have been uploaded to the server.


Notifications can be posted for the following events:

  • Filesystem mounted. The volume is now connected.

  • Filesystem unmounted. The volume has been disconnected.

  • Download complete. File download completed in the background.

  • Upload complete. File upload completed in the background.

You can adjust which notifications you want to receive in Preferences → Notifications.