Mochi

A browser-based tool to manage files and update firmware on Pixl.js-based NFC devices over Bluetooth. No app, no drivers, nothing extra.

Try it (requires Chrome, Edge, or Brave).

File management

Connect your device and manage its storage directly from the browser:

• File browser: navigate folders, rename, delete, and multi-select files
• Tree uploader: drop a local folder or files to upload with real-time progress
• Sync: diff local and device trees, push changes, and remove orphaned files
• Normalize: lowercase-rename files and folders for firmware compatibility
• Format: wipe and reformat the device drive
• NFC tag lookup: .bin files show character name and series from AmiiboAPI

Firmware update

Flash firmware directly over Bluetooth using Nordic Secure DFU. No extra tools required.

• Auto-detect device mode: connects to devices in normal or update mode from a single flow
• Connected shortcut: devices already paired from the file browser reboot into update mode automatically, no extra pairing needed
• Release picker: choose from the built-in release list or use a local .zip file
• Live progress: real-time transfer speed, progress bar, and stage-by-stage status
• Resilient transfers: packet receipt notifications, CRC verification, and automatic retry on failure
• Update notifications: badge when a newer firmware version is available

Compatible with Pixl.js-based devices (allmiibo, amiibotool, Wuzplay, Flashiibo, and others).

Development

To run the app locally:

# Generate a self-signed cert (one-time)
mkdir -p .cert
openssl req -x509 -newkey rsa:2048 -keyout .cert/key.pem -out .cert/cert.pem \
  -days 365 -nodes -subj "/CN=localhost"

# Start the dev server (HTTPS at localhost:8443)
python3 server.py --cert .cert/cert.pem --key .cert/key.pem

Click Mock device in the top bar to simulate a connected device without hardware. The button is only visible in local dev mode.

License

MIT. See LICENSE.

Libraries

• JSZip for reading firmware .zip packages in the browser
• Material Symbols for iconography
• IBM Plex Mono for monospace typography

Thanks

• solosky/pixl.js for the open-source firmware that makes all of this possible
• thegecko/web-bluetooth-dfu for the original Web Bluetooth Nordic Secure DFU implementation that served as the foundation for the firmware update module
• Nordic Semiconductor for the Secure DFU protocol specification and reference implementations
• AmiiboAPI for the NFC tag character database