SkyMountYour servers and buckets, as folders on your Mac or PC
SkyMount mounts SFTP, FTP/FTPS, Amazon S3 and Google Drive as ordinary folders: in Finder on macOS, and as a network drive in Explorer on Windows. On a Mac it needs no kernel extension, no macFUSE and no administrator rights.
Beta. The Mac version has been tested on one Mac, the Windows version on one Windows 11 PC. Keep backups of anything you work on through a mount.
Finder
~/SkyMount/Server
macOS NFS client
Built into macOS. No kext, no macFUSE, no admin rights.
SkyMount
NFSv3 on 127.0.0.1, with the file cache and offline copies.
Your storage
SFTP · FTP / FTPS · Amazon S3 · Google Drive
Explorer
S: (\\SkyMount\Server)
WinFsp driver
Installed once with admin rights. SkyMount itself runs without them.
SkyMount
Windows names and case rules, the file cache and offline copies.
Your storage
SFTP · FTP / FTPS · Amazon S3 · Google Drive
How a mount behaves
Files are cached on your computer, so folders stay quick and a dropped connection does not lose your work. This works the same on macOS and Windows.
Files download the first time you open them
A file is fetched into the cache on first read and reused while its size and modification time on the server stay the same. Files over 8 MB are read in 1 MB blocks, so opening a large video only fetches the part you play.
Saves go to a local copy, then upload
Writes land in a working copy and upload after three idle seconds, or sooner when a program closes or flushes the file. Unsent changes are journaled on disk and uploaded at the next mount if the app quits first. A failed upload retries after 5 s, 10 s, 20 s and so on, up to every 5 minutes.
Folders you keep offline open without the server
Choose Keep Offline on a folder: in Finder's right-click menu on a Mac, in the tray menu on Windows. Everything inside is downloaded and never evicted. When the server is unreachable those folders still open, also after a remount, and changes you make are uploaded when it is back.
Storage it connects to
Each connection becomes its own folder. Mount as many as you need side by side.
Any server you can ssh into.
Log in with a password or a key. Host keys are trusted on first use and pinned by SHA-256 fingerprint; a changed key is refused until you press Forget in the connection settings.
Tested with: macOS: local OpenSSH sshd, 6 to 20 MB reads and writes, rename, delete. Windows: asyncssh 2.24.1, 18 drive checks.
Older hosting accounts and NAS boxes.
Require TLS (FTPS) is on by default. Plain FTP sends the password unencrypted, so turn it off only for servers on your own network.
Tested with: macOS: pyftpdlib 2.0.1, read, 8 MB write, mkdir, rename, recursive delete. Windows: pyftpdlib 2.2.0, the same drive checks except modification times.
AWS and S3-compatible storage.
Requests are signed with SigV4, so S3-compatible services work with their own endpoint. Uploads use a single request, which limits one file to 5 GB.
Tested with: macOS: moto 5.1.4. Windows: moto 5.2.4, including 12 MB ranged reads. Read, write, folder rename, delete on both.
Through an OAuth client you create yourself.
You create the OAuth client in Google Cloud, so no third party sees your files. Deleted files go to the Drive trash. Google Docs, Sheets and Slides are not shown because they have no file contents to download.
Tested with: Not tested yet on either platform: it needs your own OAuth client.
In Finder and the menu bar
On Windows the same controls (Keep Offline, Free Up Space, Open at Login) are in the tray menu. Explorer badges and a right-click menu are not there yet.
Finder badges show what each file is doing
Green check: available offline. Blue arrows: downloading or uploading. Grey clock: waiting to upload. Red exclamation mark: an upload failed and will be retried.
- Menu bar status
- Sync arrows while files move, a filled drive while something is mounted, an outline drive otherwise.
- Mount at login
- If the network is not up yet, SkyMount tries again when it connects and every 10 s to 5 minutes until the mount succeeds.
- Free Up Space
- Removes cached copies under a folder that is not kept offline.
- Refresh from Server
- Re-reads folders now, for changes made on the server by a git pull or a deploy.
- Secrets stay in the system's credential store
- Passwords, S3 secret keys and Google tokens go to the macOS Keychain or Windows Credential Manager, never to the connections file.
- File manager metadata stays local
- ._* and .DS_Store files on a Mac, desktop.ini and Thumbs.db on Windows: none of them reach the server.
Questions
Why NFS instead of macFUSE or WebDAV?
macFUSE 5 needs an FSKit extension that could not be enabled on the development Mac. The built-in WebDAV client stalled for about 90 seconds on every mount. Loopback NFS mounts in under a second without an extension, a kext or root.
Where do mounted volumes appear?
On a Mac, under ~/SkyMount/<Name> in your home folder, not /Volumes, because ordinary users cannot create folders there. Finder lists each one as <Name>.localhost. On Windows, each connection is a network drive such as S:, labelled with the connection's name.
Can other users on my Mac reach a mount?
The NFS server listens on 127.0.0.1 only, accepts your uid or root and puts a random secret in every file handle. Another user on the same Mac who forges credentials could in theory reach a mounted volume. On a single-user Mac this is comparable to ordinary folder permissions.
Is it safe to run git on a mount?
During heavy git testing the macOS NFS client once caused a kernel panic, with a mount option SkyMount no longer uses. Keep backups of repositories you work on through a mount.
How much disk space does the cache use?
The content cache has no size limit apart from folders kept offline. Use Free Up Space on a folder to remove its cached copies.
Why does the Windows version need WinFsp?
SkyMount mounts drives on Windows through the WinFsp driver. Installing WinFsp needs administrator rights once; the SkyMount installer installs it when it is missing or older than 2.1. SkyMount itself runs without administrator rights.
Why does Windows warn when I run the installer?
Neither the installer nor the app is code-signed yet, so SmartScreen warns the first time they run.
Download SkyMount 0.1.0
Released October 27, 2026Release notes
macOS
macOS 26 or later
macOS stops the first launch because this build is not notarized by Apple yet. Open System Settings > Privacy & Security, then choose Open Anyway.
Windows
Windows 10 or 11 with WinFsp 2.1
Windows SmartScreen warns on the first run because the installer is not code-signed yet. Choose More info, then Run anyway.