Nimbus

Nimbus turns S3, Google Drive, OneDrive, SFTP and fifty more storage services into volumes on your Mac: browse them like Finder, show them in Finder, copy and sync between them, with rclone as the engine.

Nimbus is an open-source Mac app for cloud storage. Each remote from S3, Google Drive, OneDrive, SFTP and the rest of rclone’s long list becomes a volume: a pane with its capacity, its Finder presence, its files and its transfers. It doesn’t reimplement any provider: it drives rclone and puts a native interface on top, including a Finder extension so your remotes show up where your files already are.

Status: Open source
Runs on: macOS
Price: Free, GPL-3.0, signed builds included
Built with: Swift 6, SwiftUI, File Provider, rclone

Why it exists

rclone is the most capable cloud-storage engine there is, but using it means a terminal and a config file. The usual alternative is one vendor app per cloud, each with its own sync folder and its own idea of how a Mac should behave. Nimbus keeps rclone’s reach and its open config format, and drops the command line.

What it does

A remote is a volume: Select a cloud and one pane shows how full it is, whether it is in Finder, and its Files, Transfers, Finder and Settings tabs. Active transfers sit in a drawer at the bottom and as a progress capsule in the toolbar.
Your remotes, in Finder: A File Provider extension lists your volumes in Finder. Files download when you open them, and edits go back up. Or mount a remote as a network volume; those come back after a restart.
Browse like Finder: System document icons, column headers that sort, Finder’s selection rules, type-to-select, Quick Look, an inspector, and drag between clouds to copy.
Add a remote without the config file: A guided sheet asks only the questions rclone asks for that provider, and providers that use OAuth sign in through your browser. Existing rclone configs import as they are.

How it’s built

One engine, two clients

The app and its Finder extension talk to the same local rclone process through RcloneKit, a typed Swift client for rclone’s remote-control API. The engine’s port is shared through the app group, and no provider is ever reimplemented in Swift.

The rclone contract is tested, not assumed

Listing semantics and the configuration flow are pinned by tests that run the real rclone binary. The lesson written into the project: a mock proves the client’s shape, not the server’s contract.

Finder presence has one owner

Showing or hiding a volume in Finder flips the user’s intent first, then reconciles the File Provider domain in the background, and rolls back if registration fails. The sidebar switch, the header verb and the launch-time domain sync all go through the same code.

Quota from the call already being made

The status probe each remote gets on launch is rclone’s about call, which also returns used and total bytes. The capacity bars and the gauge come from that one response; providers that report no total get no gauge rather than a guess.

Finder-grade list on AppKit

The file table is a virtualized NSTableView hosting SwiftUI rows, so a ten-thousand-item folder scrolls like Finder while the rows stay declarative.

Rules the build enforces

The build fails on hard-coded font sizes, which protects Dynamic Type, and on any remote Swift package dependency.

You see The Nimbus app

You see Your remotes in Finder File Provider extension

You see Mounted volumes A remote as a Finder volume

RcloneKit A typed Swift client for rclone’s remote-control API, shared by the app and the extension

rclone serve nfs Mounted with the system’s own NFS client

rclone, running locally One engine for every provider. Nimbus never reimplements one.

S3, Google Drive, OneDrive, SFTP and more than fifty others

One engine, two clients. The app and its Finder extension talk to the same local rclone through RcloneKit; mounts go through rclone’s NFS server.

On the record

License: GPL-3.0-or-later
Providers: More than 50, through rclone
Tests: About 235 test functions across the app and RcloneKit
Third-party packages: None

Nimbus is open source and before 1.0. The signed builds are free too; Beltr and OneScribe pay for the work.

Visit the Nimbus page