A share is a folder on one device, under a name. The device that shares it keeps the files where they are; the rest of the swarm sees the share’s listing and fetches file contents on request.

Sharing a folder

From the command line, add share = "Name:/path" to the configuration (repeatable) or pass --share Name:/path when starting the node.

In the app, open Shared folders and press Choose folder…. The system’s own folder picker opens (GTK on Linux, the Storage Access Framework on Android); the picked folder shows with an editable name, then Share. Shares are saved in the app’s configuration and come back after a restart. On Android, folders in shared storage (the camera roll, Pictures, Documents, Download) can be shared; folders from cloud providers have no local path and are refused.

What gets copied, and what does not

Sharing does not copy your files into NomadFS. A background scan turns the folder into a Merkle tree:

• Files are split into content-defined chunks (FastCDC); each chunk is a block addressed by its SHA-256 hash.
• For file contents, NomadFS records only where each block is (file, offset, length) and serves it from the file itself, hashing it again on every read. Only the directory blocks and the blocks that index a file’s chunks are stored.
• The scan reuses unchanged files by size and modification time, and runs again every 30 seconds, so the share follows the folder.

A new share is listed as soon as its first scan finishes; until then the app shows it as scanning.

Browsing another device

Each device answers the others with its list of shares (their root blocks and the device’s name). Browsing a share loads one directory block at a time, so opening a folder costs one small request whatever the size of the files in it.

In the app, Browse lists every reachable device; pick one to walk its shares with breadcrumbs. On wide windows the reachable devices are also listed in the drawer.

Opening and downloading files

Reading a file asks only for the blocks that cover the bytes being read. Every block that arrives is checked against its hash before it is kept, and kept blocks are cached in the local block store, so a file opened once opens again without the other device.

The app’s viewer shows images, video, audio, PDF and text, with previous and next through the folder (arrow keys and Esc on the desktop). It reads the file in 4 MiB pieces, so it shows progress and works the same on Android. Download saves a copy in ~/Downloads/NomadFS (the shared Download/NomadFS folder on Android); a name that exists already gets a number.

The Linux mount

On Linux everything can be mounted as an ordinary folder that any program can open:

<mount>/
├── Laptop/
│   └── Documents/…
├── Xiaomi M2007J20CG/
│   └── Camera/…
└── Swarm/…

• <mount>/<device>/<share>/… is read-only (files 0444, folders 0555).
• <mount>/Swarm is the swarm folder and is writable.

From the command line:

nomadfs --mount ~/NomadFS

It runs the node, mounts, and unmounts on Ctrl-C or SIGTERM. In the desktop app, the Mount tab mounts at ~/NomadFS by default (Change picks another folder), and Open folder opens it in your file manager. The tray icon has the same switch, so the mount keeps working with the window closed; Quit in the tray unmounts before exiting. Mounting over a stale NomadFS mount at the same folder clears it first.

The driver speaks the kernel’s FUSE protocol on /dev/fuse directly: there is no libfuse or libc dependency. fusermount3 performs the unprivileged mount, so install fuse3 if it is missing. Mounting is available on Linux only; the Mount tab does not appear elsewhere.