Nitro Print Service SDK

A lightweight TypeScript/JavaScript SDK for communicating with the Nitro Print Service to discover printers and send print jobs.

Installation

npm install nitro-print-service-sdk

Requirements

Before using this package, make sure your Nitro Print Service is running on the machine.

The SDK communicates with:

http://127.0.0.1:9191

Important: Print Data

The print() function expects the print data as a Base64-encoded string.

You need to create the raw ESC/P commands for your printer, convert them into a Buffer, and then convert that buffer to Base64 before sending it to the SDK.

For example:

const label = new BrotherLabelBuilder()
  // --- Item Number ---
  .align("center")
  .bold(true)
  .fontSanSerif()
  .fontSize(35)
  .text(`#: ${data.itemNumber}`)
  .lineBreak(1)
  .bold(false)

  // --- Details ---
  .align("left")
  .fontSize(22)
  .lineSpacing(40)
  .text(`Name:   ${data.itemName}\n`)
  .text(`Stream: ${data.streamName.toUpperCase()}\n`)
  .text(`Date:   ${formattedDate} ${formattedTime}`);

// Build the raw ESC/P binary payload
const payloadBuffer: Buffer = label.buildPayload();

// Convert the raw payload to Base64
const base64Data = payloadBuffer.toString("base64");

You can then pass the Base64 data to print():

import { print } from "nitro-print-service-sdk";

const result = await print({
  printerName: "Brother QL-820NWB",
  base64Data,
});

console.log(result);

If you don't specify printerName, the Nitro Print Service can use the default printer:

const result = await print({
  base64Data,
});

Get Available Printers

Use getPrinters() to retrieve the printers available on the machine:

import { getPrinters } from "nitro-print-service-sdk";

try {
  const printers = await getPrinters();

  console.log(printers);
} catch (error) {
  console.error("Failed to get printers:", error);
}

Example response:

[
  {
    name: "Brother QL-820NWB",
    displayName: "Brother QL-820NWB",
    description: "Brother Label Printer",
    isDefault: true
  }
]

Print

The print() function accepts a PrintRequest:

interface PrintRequest {
  printerName?: string;
  base64Data: string;
}

Example:

import { print } from "nitro-print-service-sdk";

try {
  const result = await print({
    printerName: "Brother QL-820NWB",
    base64Data,
  });

  console.log(result);
} catch (error) {
  console.error("Print failed:", error);
}

API

getPrinters()

Returns all available printers.

getPrinters(): Promise<Printer[]>

print(request)

Sends the Base64-encoded ESC/P print data to the selected printer.

print(request: PrintRequest): Promise<PrintResponse>

Types

Printer

interface Printer {
  name: string;
  displayName?: string;
  description?: string;
  isDefault: boolean;
}

PrintRequest

interface PrintRequest {
  printerName?: string;
  base64Data: string;
}

PrintResponse

interface PrintResponse {
  status: "success" | "error";
  message: string;
}

PrintersResponse

interface PrintersResponse {
  status: "success" | "error";
  message?: string;
  defaultPrinter: string | null;
  printers: Printer[];
}

Error Handling

Both getPrinters() and print() throw an Error when the request fails.

try {
  const printers = await getPrinters();

  const result = await print({
    base64Data,
  });
} catch (error) {
  console.error(error);
}

Local Nitro Print Service

Make sure the Nitro Print Service is running before using this SDK.

The SDK communicates with:

http://127.0.0.1:9191

Available endpoints:

GET  /printers
POST /print

The SDK does not start the Nitro Print Service. The service must already be running on the user's machine.