Web (browser)

@thermal-label/labelwriter-web is a browser-only package that uses the WebUSB API to communicate with Dymo LabelWriter printers directly from the browser — no backend, no drivers.

Browser support

Browser	Support
Chrome 61+	✅
Edge 79+	✅
Firefox	❌
Safari	❌
Samsung Internet	❌

WebUSB requires a secure context — the page must be served over HTTPS or from localhost.

Install

npm install @thermal-label/labelwriter-web

Quick start

import { requestPrinter } from '@thermal-label/labelwriter-web';

// Opens the browser's USB device picker, filtered to known LabelWriter PIDs.
// Must be called in response to a user gesture (click, keypress, etc.)
const printer = await requestPrinter();

await printer.printText('Hello from the browser!', { density: 'high' });
await printer.disconnect();

Connect to a known device

If you already have a USBDevice from navigator.usb.getDevices():

import { fromUSBDevice } from '@thermal-label/labelwriter-web';

const [usbDevice] = await navigator.usb.getDevices();
const printer = fromUSBDevice(usbDevice);
await printer.printText('Reconnected!');

Printing images

// From ImageData (e.g. from a <canvas>)
const canvas = document.querySelector('canvas');
const ctx = canvas.getContext('2d');
const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
await printer.printImage(imageData, { threshold: 128 });

// From a URL
await printer.printImageURL('/logo.png', { rotate: 90 });

Live demo

Try it in your browser: Demo

NFC label lock

550 series

The LabelWriter 550 series enforces NFC chip validation on label rolls at the hardware level. Non-certified labels will be rejected. See Getting started — NFC label lock.

API

requestPrinter()

Calls navigator.usb.requestDevice() filtered to all known LabelWriter PIDs and wraps the selected device in a WebLabelWriterPrinter. Must be called inside a user gesture handler.

fromUSBDevice(device)

Wraps an existing USBDevice in a WebLabelWriterPrinter. Throws if the device is not a recognised LabelWriter model.

WebLabelWriterPrinter

Member	Type	Description
device	USBDevice	Underlying USB device
descriptor	DeviceDescriptor	Device metadata (name, protocol, etc.)
getStatus()	Promise<PrinterStatus>	Read printer status
print(bitmap, options?)	Promise<void>	Print a LabelBitmap
printText(text, options?)	Promise<void>	Render text and print
printImage(imageData, options?)	Promise<void>	Print from ImageData
printImageURL(url, options?)	Promise<void>	Load URL and print
recover()	Promise<void>	Send error recovery
isConnected()	boolean	Whether the device is open
disconnect()	Promise<void>	Close USB connection