@lacspace/xlsx

Write real Excel (.xlsx) files with zero dependencies — no SheetJS, no exceljs, no headless browser.

"Export to Excel" for any dashboard — without the weight. A .xlsx file is just a ZIP of a few XML parts, so this builds the bytes directly (the same trick as @lacspace/pdf). The incumbents are large and Node-centric; this is tiny and runs on Node, edge and the browser.

• 📊 Objects → a sheet (headers from keys or explicit columns), or array-of-arrays
• 🔢 Correct types — string, number, boolean and real Excel dates
• 🅱️ Bold headers, column widths, multiple sheets
• 📦 Output Uint8Array — stream it, download it, save it · zero deps · isomorphic

Install

npm install @lacspace/xlsx      # or pnpm add / yarn add / bun add

Objects → spreadsheet

import { jsonToXlsx } from "@lacspace/xlsx";
import { writeFileSync } from "node:fs";

const bytes = jsonToXlsx([
  { name: "Ada Lovelace", signups: 12, active: true, joined: new Date("2026-01-15") },
  { name: "Alan Turing",  signups: 7,  active: false, joined: new Date("2026-02-01") },
]);

writeFileSync("users.xlsx", bytes);                 // Node
// or serve a download:
return new Response(bytes, {
  headers: {
    "content-type": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "content-disposition": 'attachment; filename="users.xlsx"',
  },
});

Multiple sheets, columns & widths

import { Workbook } from "@lacspace/xlsx";

const bytes = new Workbook()
  .sheet("Users", rows, {
    columns: [
      { header: "Name", key: "name", width: 28 },
      { header: "Sign-ups", key: "signups", width: 12 },
    ],
  })
  .sheet("Totals", [["Metric", "Value"], ["Users", 2], ["Revenue", 4500]], { header: true })
  .toBytes();

API

| Export | Description | | --- | --- | | jsonToXlsx(rows, opts?) | array of objects → .xlsx bytes | | aoaToXlsx(rows, opts?) | array of arrays → .xlsx bytes | | new Workbook().sheet(name, rows, opts?) | multi-sheet builder | | .toBytes() · .toBase64() | output | | columnLetter(i) | 0 → "A", 26 → "AA" |

Values map to Excel types automatically (Date → a real date cell). Free under the Lacspace Free Licence.

Licensing

This package is free under the Lacspace Free Licence — permissive freedoms. Use it in personal and commercial projects at no cost; just keep the notice.

Not every Lacspace package is free. We also offer Commercial, Client-specific and Private packages under separate terms — see the Lacspace Licence Centre.

The Lacspace Developer Platform

@lacspace/xlsx is part of 63 zero-dependency, isomorphic TypeScript packages — one standard library for the modern web. Explore the ecosystem:

• 📦 This package, documented — https://developer.lacspace.com/packages/xlsx
• 🗂️ All 63 packages — https://developer.lacspace.com/packages
• 🧭 Developer handbook — guides & runnable recipes — https://developer.lacspace.com/handbook
• 🧪 Live playground — run any package in your browser — https://developer.lacspace.com/playground
• 🖥️ Finished app templates — https://templates.lacspace.com
• 🚀 Scaffold a full app — npm create lacspace-app@latest

Free under the Lacspace Free Licence — a permissive, free-to-use licence.