How CloudMount works

CloudMount has three layers. Knowing them explains most of its behaviour, including the differences between platforms and between storage services.

 Your apps ─ Files app, file pickers, Explorer, Office, …
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 The operating system's file API
     Android: Storage Access Framework     Windows: Cloud Files API
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 CloudMount ─ turns file requests into rclone operations,
     │        queues uploads, caches, tracks changes
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 rclone, running inside the app ─ one backend per kind of storage
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 Your storage ─ Google Drive, S3, SFTP, … reached directly over the internet

rclone, inside the app

rclone is the open-source tool that knows how to talk to more than 70 storage products through some 60 backends, one per kind of storage. CloudMount builds a real rclone, the same code as the command-line tool, into the app, with every backend included. Your drives are rclone remotes, stored in a standard rclone.conf, so you can bring your configuration along from rclone on a computer and take it back.

Because CloudMount uses rclone’s backends unchanged, what a drive can do is what rclone’s backend for it can do. The Backends pages describe each one, and explain how a backend’s capabilities show up in the app: whether a copy happens on the server or through your device, whether modification times survive, and so on.

No server in the middle

CloudMount has no server of its own between you and your storage. Your device connects to the storage service directly, sign-ins happen on your device, and your files and credentials are never sent to us. The only things CloudMount sends to its developer are optional, anonymous usage and crash reports; see Security and privacy.

The operating system’s own file API

Rather than a separate file manager, CloudMount plugs your drives into the system so every app can use them:

• On Android, CloudMount is a document provider in the Storage Access Framework (SAF). Your drives appear in the Files app and in every app’s “open” and “save” dialogs, next to local storage and other clouds. Apps ask CloudMount for a folder listing or a file, and CloudMount answers through rclone: listings come from the drive, file contents stream from it, and saved files upload in the background. See The Files app.
• On Windows, CloudMount uses the Cloud Files API, the technology behind OneDrive’s files on demand. Each drive is a folder in your user profile whose files are placeholders that download when opened, with sync status icons in Explorer. See File Explorer.

The two APIs work very differently, and that’s the biggest source of differences between the platforms. Android’s SAF is on demand: nothing is stored on the phone unless you ask for it, and each app request goes to the drive. Windows’ Cloud Files API is sync: opened files stay on the PC as real files, and CloudMount keeps both sides in step. See Android and Windows compared.

Shared core

Both apps share the same Go core around rclone, so a drive behaves the same way on both: the same backends, the same options in the Add drive wizard and the same rclone.conf format. The apps around it are native: Kotlin and Jetpack Compose on Android, WinUI 3 on Windows.