Mountain Duck lets you mount server and cloud storage as a disk on your desktop. With Smart Synchronization, files are synchronized to the local disk when opened to allow offline usage and changes are uploaded in the background as soon as a connection is available. Open remote files with any application and work like on a local volume. Transfer files using Finder to remote servers, fast. Select files and folders to always keep offline on your computer. Other files are downloaded and cached on demand only and otherwise do not take space on your local disk. Encryption for data at rest using Cryptomator interoperable vaults prevent unauthorized access regardless of the server or cloud storage infrastructure.

Based on the solid open source foundation of Cyberduck, all major protocols are supported to connect to just about any server you want. Including FTP, SFTP, WebDAV, Azure Cloud Storage, Amazon S3, Google Cloud Storage, Google Drive, Dropbox, Backblaze B2 & OpenStack Swift.

What’s New

Version 4.2.3

• Failure saving new Microsoft Office files with "File Locking" enabled
• Failure opening files in Online connect mode with "Enable Cache" disabled
• Missing folders with delete marker on placeholder for buckets with versioning enabled (S3)
• Failure writing multipart upload when saving file from editor using small write chunk sizes (S3)

Ratings and Reviews

2.9 out of 5
16 Ratings

16 Ratings

timmattison ,

Like many other cloud mounting apps, this one has issues

Copying files from S3 to Dropbox actually worked quite well. However, I see the disks randomly disconnect, fail to refresh, and just exhibit behavior that makes it generally unusable for anything other than bulk, on-demand tasks.

If you plan on mounting some remote storage (SFTP) to work with an IDE to do development this is probably not a good choice.

Also, I've run into the application hanging when trying to remove files with "rm" via the terminal from S3. There didn't seem to be a way to get the command to exit, even with CTRL-C, but the file did actually delete.

Federmanhoyos ,

Really God But Support ?

I bought the application because its option of offline mode. And so far the application has been working pretty well. The complaint is that I cant open PDF files ( Preview or any other editor ) and write notes in the pdf. Every time I do that I receive a messages telling me that is not allowed and basically force me to save the document with a different name.

I have emailed to the product support, but guess what? No answer at all. Nothing.

Fixing the PDF editing error and fixing his support service I will 5 starts to the product

Developer Response ,

Files opened in and edited cannot be saved at the original location but the message "The original document can't be changed, so a duplicate with your changes has been created" is displayed in the title bar. As a workaround you can set a custom mount point in Preferences → Connection → Mount Location for volumes such as a ~/Volumes/ folder in your home directory. Also refre to our FAQ or known issues at

Chuck Emary ,

Does Not Work

I tried the demo version of this and it seemed to function properly. When I installed the paid version it failed to run properly. There were file permissions of some sort. I tried a bunch of things to no avail. Very frustrating. Sent an email to support and so far crickets. Will be requesting a refund.


David Kocher
120.2 MB

macOS 10.12 or later, 64-bit processor


English, Arabic, Bulgarian, Catalan, Croatian, Czech, Danish, Dutch, Estonian, Finnish, French, Georgian, German, Greek, Hebrew, Hungarian, Italian, Japanese, Korean, Latvian, Norwegian, Polish, Portuguese, Romanian, Russian, Serbian, Simplified Chinese, Slovak, Slovenian, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Ukrainian, Welsh

Age Rating
Unrestricted Web Access


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.