NEJE Web Engraver

Control a NEJE Master 2 laser engraver straight from the browser over USB. No install, no account, works offline. Built and tested with a NEJE Master 2 Mini.

Features

Connection

• USB via Web Serial in Chrome, Edge or Opera on Windows, macOS and Linux. A built-in simulator lets you try everything without a machine, in any browser.
• If the engraver goes silent, the app says so. The USB bridge keeps the port open even when the board is off or hung, so this cannot be detected any other way. Connection problems link straight to the Help tab.

Engraving

• The Engrave panel stays at the top: Trace frame, a red Stop engraving button, Pause and Start.
• Two-phase progress. The machine first receives the whole image and only then burns, so the panel shows two steps. Sending to engraver uses the receipt the device confirms. Engraving uses the device's own progress and clock. While it burns, the panel shows elapsed time, time left and the expected finishing time. Afterwards it shows "Finished at …, took …".
• Safety:
  • a confirmation dialog before every job, with goggle and material checks,
  • STOP in the header, in the panel and on the Esc key,
  • no command can reach the machine while image data is streaming,
  • a stop during the upload pads the rest with blank dots before cancelling.
• Trace frame follows only the area that will actually burn, with blank margins trimmed.

Image, text and patterns (tabs Image and Text)

• Any format: PNG, JPEG, WebP, GIF, BMP, AVIF and SVG. SVG stays vector until it is rasterised at the machine's resolution. Drop an image anywhere, paste it, or use the file picker.
• Size in mm, rotation, mirroring, brightness, contrast, threshold, Floyd–Steinberg or Atkinson dithering, and invert, with a live 1:1 dot preview on a millimetre grid.
• Text tool: type text, pick a font, bold or italic and alignment. It becomes a vector motif.
• Test patterns for focus, line widths and calibration, inserted at their calibrated size.

Position and head (tab Position and the work area)

• Drag the image, use the arrow keys (1 mm, or 10 mm with Shift), type coordinates, or centre it.
• The head position is always visible, as a crosshair and as text. It is known after Go home, updated with every move, and live while burning from the device's position reports.
• Move head by clicking on the work area, or with the arrow keys as a keyboard alternative.
• Dimension lines: image size and distances to the edges, head distances, and the head offset from the image corner. The values are also listed as text.
• The connection check after connecting (go home and trace a 5 mm square, laser off) can be switched off.

Laser, machine and history

• Material presets: NEJE's reference burning times (wood, bamboo, leather, acrylic …) and your own, plus a rough time estimate.
• Machine settings, stored in the engraver itself: pointer brightness when idle, motion-detection sensitivity, and motor speed (Slowest to Fast, as in NEJE's Windows software).
• History of every job, with its image and all settings. You can open an entry, reuse only its settings, or drop in a new image to swap the motif and keep everything else. The start dialog asks whether to save, and yes is the default.
  • History lives in this browser's IndexedDB. Export writes everything to a single JSON file for backup or for moving to another computer, and Import reads it back after validating it.

Everywhere

• 8 languages: English, Čeština, Deutsch, Français, Español, Italiano, Polski, 中文. The app follows the browser language and has a manual switch.
• Accessible: built to WCAG 2.2 AA. axe checks every tab in light and dark mode, everything works with the keyboard alone, and it works with screen readers.
• Offline: an installable PWA. After the first visit it runs without a network.

Use it

1. Open the deployed app, or run it locally (see below), in Chrome or Edge.
2. Close the NEJE vendor app if it is running. Only one program can use the serial port.
3. Click Connect engraver and pick the USB serial port (wchusbserial… / COM…).
   • On Windows the CH340 driver may be needed.

[!WARNING] Laser light damages eyes and can start fires. Always wear laser safety goggles, never leave the machine unattended, and keep its power switch within reach. The software STOP is no substitute for it.

Engravings look shifted or blurry?

The software cannot detect this, because the steppers have no feedback. These are the usual causes:

• Lines shift part-way through a job and stay shifted. This happens with the vendor app too. The NEJE manual says a loose belt causes image offset. Tighten the belt at its two adjustment points and check that the motor pulley's grub screws are tight. With the machine off, the head should move freely by hand along the whole axis. A slower motor speed (Machine tab) can also help.
• Everything is blurry. Set the laser 30–50 mm above the material (usually 40 mm) and turn the focus cap until the dot is as small as possible. The Focus and resolution test pattern shows the result.

Project status

Area	Status
Connect, identify, telemetry, reconnect, homing, head moves	✅ verified on a Master 2 Mini (automated hardware test)
Laser parameters (power, burn time)	✅ verified in real burns, stored by the device across power cycles
Machine settings: pointer brightness, motion detection	Implemented to the vendor protocol, not yet changed on hardware
Motor speed	Values 0–3 (Slowest–Fast) as in NEJE's Windows software for the Master 2 family; the Mini reports 2 (Medium). Not yet changed on hardware
Job upload and burn, trace frame, cancel	✅ verified with a real calibration burn (traffic captured, see docs/PROTOCOL.md)
Pause/resume	Implemented to the vendor protocol, covered by simulator tests, not yet tried on hardware
Odd-row bit order	Two variants selectable (Advanced) until a calibration burn decides
Older KZ / BL / Master 1 boards (4-byte protocol)	Not supported

The protocol is documented in docs/PROTOCOL.md.

Development

Requirements: Node.js 22 or newer.

npm install
npm run dev        # http://localhost:3000
npm run check      # typecheck, lint, unit tests, build, end-to-end tests

Script	What it does
npm run build	Static export to out/, deployable to any static host
npm run preview	Serves out/ on http://localhost:4173
npm test	Vitest unit tests: protocol bytes, parser, bitmap packing, dithering, session against the simulator, history file validation, text-to-SVG escaping, translations
npm run test:e2e	Playwright against the production build, with the simulator instead of a machine. Covers every tab, axe WCAG 2.2 AA scans in both colour schemes, keyboard-only use, history export/import, languages and offline mode
npm run test:hardware	Optional. Drives the real UI against a connected engraver, e.g. NEJE_PORT=/dev/cu.wchusbserial3130 npm run test:hardware -- device. Its relay refuses anything that could fire the laser. A calibration burn with traffic capture needs a second opt-in (NEJE_ALLOW_BURN=1 … -- burn, see tests/hardware/burn.spec.ts)

Architecture

src/
  lib/protocol/   wire format, message decoding, bitmap packing, NejeSession (no DOM, fully unit tested)
  lib/transport/  Web Serial, simulator (real captured frames), Playwright hardware bridge
  lib/imaging/    file decoding (raster + SVG), dithering, rasterisation at device resolution
  lib/            job settings model + validation, history (IndexedDB) and its export file, presets,
                  machine settings, text-to-SVG, test patterns, storage
  i18n/           typed messages per locale, browser language detection
  hooks/ components/ app/   React UI (Next.js App Router, static export)
public/sw.js      offline service worker

• NejeSession exposes an immutable snapshot through subscribe/getSnapshot, so React reads it with useSyncExternalStore.
• All job settings are one validated object (JobSettings). History stores it next to the image, which is what makes swapping the motif possible.
• English is the source locale. TypeScript and the unit tests enforce that every locale has the same keys and placeholders, and that accessible names contain their visible labels (WCAG 2.5.3).

Deploy

• Vercel: import the repository. No configuration is needed.
• Any static host (GitHub Pages, Cloudflare Pages, Netlify, nginx): npm run build and upload out/. For a sub-path, build with NEXT_PUBLIC_BASE_PATH=/sub-path.

Web Serial and the service worker need HTTPS, or localhost.

Contributing

Issues and pull requests are welcome, especially:

• captures from other Master 2 models,
• results of calibration burns,
• translations.

Please run npm run check before opening a pull request.

Disclaimer

This is an independent open-source project. It is not affiliated with or endorsed by NEJE (Shenzhen ZhiXinJie Technology Co., Ltd.). The protocol was documented for interoperability with hardware the author owns, and no vendor code or assets are included. Use at your own risk.

License

MIT