JavaScript Quickstart

The one-line version, for reference:

curl -X POST "https://api.labelzoom.com/api/v2/convert/zpl/to/pdf" -H "Authorization: Bearer YOUR_API_KEY" -H "Content-Type: text/plain" -d '^XA^FO50,50^ADN,36,20^FDLabelZoom^FS^XZ' --output label.pdf

The same conversion with fetch (Node.js 18+, Bun, Deno, or serverless runtimes):

import { writeFile } from "node:fs/promises";

const zpl = "^XA^FO50,50^ADN,36,20^FDLabelZoom^FS^XZ";

// The API key is optional — omit the Authorization header if it isn't set.
const headers = { "Content-Type": "text/plain" };
if (process.env.LABELZOOM_API_KEY) {
  headers.Authorization = `Bearer ${process.env.LABELZOOM_API_KEY}`;
}

const response = await fetch(
  "https://api.labelzoom.com/api/v2/convert/zpl/to/pdf?label.width=4&label.height=6&dpi=203",
  {
    method: "POST",
    headers,
    body: zpl,
  },
);

if (!response.ok) {
  throw new Error(`Conversion failed: ${response.status} ${await response.text()}`);
}

await writeFile("label.pdf", Buffer.from(await response.arrayBuffer()));
console.log("Wrote label.pdf");

Converting a PDF to ZPL

Send the file bytes instead of text:

import { readFile } from "node:fs/promises";

const pdf = await readFile("shipping-label.pdf");

const headers = { "Content-Type": "application/pdf" };
if (process.env.LABELZOOM_API_KEY) {
  headers.Authorization = `Bearer ${process.env.LABELZOOM_API_KEY}`;
}

const response = await fetch("https://api.labelzoom.com/api/v2/convert/pdf/to/zpl", {
  method: "POST",
  headers,
  body: pdf,
});

const zpl = await response.text();

Notes

• Call the API from your backend — never expose your key in browser code.
• All endpoint patterns, formats, and parameters are in the quickstart and the Swagger reference.