Free offline NFC spool scanner for the Snapmaker U1 — auto-registers spools in Spoolman, tracks usage via Moonraker.

SpoolScan is a free Android NFC scanner for filament spools on the Snapmaker U1. Tap a spool with your phone, the app looks it up (or registers it) in Spoolman and assigns it to a print slot via Moonraker. Reads OpenPrintTag, OpenSpool and SpoolCompanion tags. No subscription, no account, no cloud.

Available in English and German.

Scan	Known spool	OpenPrintTag spool	Manual entry
Tap a tag to scan	Live remaining weight from Spoolman	OpenPrintTag auto-registered	Manual entry for blank tags

• Reads three NFC tag formats: SpoolCompanion (SPOOL:3), OpenSpool (JSON), and OpenPrintTag (Prusa's new open standard, openprinttag.org)
• Three-stage spool lookup: Spoolman ID → NFC hardware UID → unknown (then auto-create)
• Self-healing UID linking: After the first scan, the chip's NFC UID is stored in Spoolman (extra.nfc_uid). Future scans of the same physical tag are matched instantly, regardless of tag format.
• Automatic spool registration: Unknown spools are created in Spoolman on the spot — vendor, filament and spool entries are added automatically when needed.
• Hybrid create flow:
  • OpenPrintTag/OpenSpool with data → confirmation dialog with prefilled values
  • SpoolCompanion / blank NTAG → manual entry form prefilled with what was on the tag
• Consumption tracking via Moonraker's [spoolman] integration — the app sets the active spool, Moonraker reports usage, the DetailScreen shows the current remaining weight on every scan.
• Spoolman stays unmodified — uses only the official REST endpoints plus the standard extra field schema. Update Spoolman freely without breaking the app.
• Language toggle: Deutsch / English
• Works fully offline for tag reading — only needs your local network for Spoolman/Moonraker calls.

• Android phone with NFC
• Snapmaker U1 with Moonraker running
• Spoolman reachable on your local network
• NFC tags on your spools (any of the three supported formats — or even blank NTAGs, which the app will register on first scan)

To make the spool / RFID workflow work end-to-end on the printer side, three things are required on the Snapmaker U1:

1. Snapmaker official firmware ≥ v1.2.0 — OpenRFID support was introduced in the official v1.2.0 firmware. Older versions don't expose the RFID subsystem the rest of this stack relies on.
2. paxx12 SnapmakerU1-Extended-Firmware (e.g. release v1.2.0-paxx12-14 or newer) — extended firmware built on top of official v1.2.0 that adds full OpenRFID support (details). Without this firmware the RFID / multi-tool spool tracking on the printer doesn't work, and SpoolScan's slot assignments won't be reflected in Spoolman or counted during prints.
3. Davo1624 snapmaker-u1 spoolman setup — Klipper macros that map the four tool slots (T0–T3) to Spoolman channels (SET_CHANNEL_SPOOL, t<slot>__spool_id persistent variables, etc.). Required for SpoolScan's per-slot assignment to register as the "Aktive Rolle" in Spoolman.

If you don't have these installed yet, install them on the printer first. SpoolScan itself will still launch without them, but slot assignment, "Aktive Rolle" updates and consumption tracking will not work.

1. Download the latest app-release.apk from the Releases page
2. On your Android phone: Settings → Security → allow installation from unknown sources
3. Open the APK file and install

Open the app → tap the settings icon (top right):

For Spoolman to receive filament usage automatically from Moonraker, add this block to ~/printer_data/config/moonraker.conf on the Snapmaker U1:

[spoolman]
server: http://192.168.1.181:7912
sync_rate: 5

(Adjust the URL for your environment.) Then restart Moonraker:

sudo systemctl restart moonraker

Once active spool is set via SpoolScan, Moonraker will reduce remaining_weight in Spoolman during prints. The DetailScreen displays the live remaining weight on every scan.

1. Open SpoolScan
2. Hold the phone to a spool's NFC tag
3. Known spool: brand, material, color and remaining weight from Spoolman are shown immediately
4. Unknown spool: confirmation dialog (auto-fill) or entry form opens — confirm/save and the spool is registered
5. Tap T0 / T1 / T2 / T3 to assign the spool to that slot

SpoolCompanion:

SPOOL:3
FILAMENT:3

OpenSpool (JSON):

{"protocol":"openspool","spool_id":3,"brand":"Sunlu","type":"PETG","color_hex":"000000"}

OpenPrintTag (JSON):

{"standard":"openprinttag","brand":"Prusament","material":"PETG","color_hex":"1a1a1a","weight_total":1000,"weight_remaining":850,"print_temp":240}

Spec: https://openprinttag.org/

Scan ─► UID + payload extracted
       │
       ├─► Stage 1: tag carries a Spoolman ID? → fetch /spool/{id}
       ├─► Stage 2: search /spool list for extra.nfc_uid match
       └─► Stage 3: create new spool (auto from tag data, or manual form)

Found ─► Self-heal: store the chip UID on the matched spool if missing
       ─► Show details + remaining weight
       ─► Pick slot → Moonraker SET_ACTIVE_SPOOL
       ─► Print → Moonraker reports usage → Spoolman updates remaining_weight

• Flutter 3.x (Dart)
• nfc_manager — NFC tag reading
• http — Moonraker & Spoolman API
• shared_preferences — settings storage
• mockito — test mocks
• Moonraker REST API + [spoolman] integration
• Spoolman REST API v1

git clone https://github.com/YOUR_USERNAME/spoolscan.git
cd spoolscan
flutter pub get
flutter build apk --release

This project is licensed under the GNU General Public License v3.0 — see LICENSE for details.

If you find this project useful, consider buying me a coffee! ☕