> ## Documentation Index
> Fetch the complete documentation index at: https://3to1go.docs.thesteau.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Edge overview
> The app that runs on each machine, finds marked folders, encrypts them, and uploads them to Central.
Edge is the 3to1go app that **makes** backups. Run one Edge on every machine whose files you want to protect. Each Edge works on its own and only needs to reach Central to upload.
## What Edge does
* **Finds backup jobs** by scanning for folders that contain a `.upload_dir` marker.
* **Detects changes** with a path-and-size fingerprint, so unchanged folders aren't uploaded again.
* **Builds and encrypts archives** as `tar.zst` files. The key stays on Edge unless you copy it for safekeeping or browser-based downloads; it is never sent to Central's server.
* **Uploads to Central** in chunks, resuming and retrying when the connection drops.
* **Runs on a schedule** you set with a cron expression, weekly by default.
* **Restores snapshots** from Central back into the original folder.
* **Sends notifications** to ntfy and runs your own scripts around each job.
## Folders it uses
| Inside the container | Holds |
| - | - |
| `/scan` | The folders Edge can see and back up. You choose what's mounted here. |
| `/config` | Settings database, `encryption.key`, instance ID, trusted certificates |
| `/data/state` | Per-job backup state |
| `/data/spool` | Archives waiting to upload |
| `/hook-scripts` | Scripts you upload for [hooks](/edge/hooks) |
Back up Edge's `config` folder, especially `encryption.key`. Without that key, this Edge's snapshots **cannot be decrypted**. See [Encryption key](/edge/encryption-key).
## The Edge UI
Open `http://:6556/`. The main page shows:
* **Selected Jobs**: each backup job, its last state, the size of its last backup, and buttons to browse files, force an upload, restore, or edit it.
* **Directories Under Scan Root**: a folder browser for choosing what to back up. Turn on **Show hidden** to see hidden folders.
