Read and Write Excel Files in Bun with bun-excel

#bunjs #typescript #excel #csv

If you are building a Bun app and need to export Excel or CSV files, bun-excel provides a Bun-native API for common spreadsheet workflows.

It supports .xlsx, CSV, styles, formulas, hyperlinks, streaming exports, and Bun file targets such as local files, Bun.file(), and S3File.

Install

bun add bun-excel

Write an Excel file

import { writeExcel, type Workbook } from "bun-excel";

const workbook: Workbook = {
  worksheets: [
    {
      name: "Report",
      columns: [{ width: 20 }, { width: 12 }],
      rows: [
        {
          cells: [
            { value: "Name", style: { font: { bold: true } } },
            { value: "Score", style: { font: { bold: true } } },
          ],
        },
        { cells: [{ value: "Alice" }, { value: 95 }] },
        { cells: [{ value: "Bob" }, { value: 87 }] },
      ],
    },
  ],
};

await writeExcel("report.xlsx", workbook);

Read it back

import { readExcel } from "bun-excel";

const workbook = await readExcel("report.xlsx");

for (const sheet of workbook.worksheets) {
  for (const row of sheet.rows) {
    console.log(row.cells.map((cell) => cell.value).join(" | "));
  }
}

Stream large exports

For large reports, you can write rows incrementally:

import { createExcelStream } from "bun-excel";

const stream = createExcelStream("large-report.xlsx", {
  sheetName: "Data",
  columns: [{ width: 10 }, { width: 30 }, { width: 15 }],
});

stream.writeRow(["ID", "Product", "Price"]);

for (let i = 0; i < 100_000; i++) {
  stream.writeRow([i + 1, `Product ${i + 1}`, Math.random() * 1000]);
}

await stream.end();

CSV support

import { writeCSV, readCSV } from "bun-excel";

await writeCSV("users.csv", [
  ["Name", "Age"],
  ["Alice", 28],
  ["Bob", 31],
]);

const rows = await readCSV("users.csv");