Universal JavaScript/TypeScript library for importing and exporting tabular data.

Supports browser and Node.js environments and provides a unified API for converting spreadsheets, JSON data, and tabular documents.

Used in Unsonet projects, including the Excelsior extension.

On the Excelsior PDF demo page, data is exported via the excelsior-data-converter.

Try it in action: DEMO

• Import spreadsheets and JSON files into structured data
• Export structured data to multiple formats
• XLSX / XLS support
• CSV / TSV support
• PDF, DOCX, images and other export formats
• Browser support
• Node.js support
• TypeScript support
• Command-line interface
• Client-side processing
• No server required
• No AI dependencies
• No OCR dependencies

npm install @unsonet/excelsior-data-converter

or

pnpm add @unsonet/excelsior-data-converter

The ImportService converts files represented as FileItem-like objects into structured JavaScript data.

import { ImportService } from '@unsonet/excelsior-data-converter';

const service = new ImportService();

const result = service.convertFileItemToData({
  name: 'employees.xlsx',
  type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  size: file.size,
  base64
});

console.log(result);

The base64 property can contain either a raw Base64 string or a Data URL.

By default, nested spreadsheet column names can be converted into nested objects.

Use flatStructure: true to keep the original flat structure:

const result = service.convertFileItemToData(
  {
    name: 'employees.xlsx',
    type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
    size: file.size,
    base64
  },
  {
    flatStructure: true
  }
);

Use ExportService.download() to export an array of objects.

import { ExportService } from '@unsonet/excelsior-data-converter';

const service = new ExportService();

const data = [
  {
    id: 1,
    name: 'John'
  },
  {
    id: 2,
    name: 'Alice'
  }
];

await service.download(data, 'employees', 'xlsx');

The arguments are:

service.download(
  data,
  fileName,
  extension
);

For example:

await service.download(data, 'employees', 'csv');

or:

await service.download(data, 'employees', 'pdf');

The export process is performed locally without sending data to a server.

ExportService also provides methods for converting HTML content into different formats.

For example:

const service = new ExportService();

await service.save(
  {
    type: 'pdf',
    elementIdOrContent: 'my-table'
  },
  'employees'
).toPromise();

The elementIdOrContent property can contain either an element ID or an HTMLElement.

The package includes a command-line interface for importing and exporting files.

After global installation:

npm install -g @unsonet/excelsior-data-converter

you can use:

excelsior-data-converter

Convert a supported input file into JSON:

excelsior-data-converter import <file>

Example:

excelsior-data-converter import employees.xlsx

Save the result to a file:

excelsior-data-converter import employees.xlsx -o result.json

Pretty formatted JSON:

excelsior-data-converter import employees.xlsx --pretty

Flat structure:

excelsior-data-converter import employees.xlsx --flat

Convert a JSON file into another supported format:

excelsior-data-converter export <file> --to <extension>

Example:

excelsior-data-converter export employees.json --to xlsx

Export to CSV:

excelsior-data-converter export employees.json --to csv

Specify the output file:

excelsior-data-converter export employees.json --to xlsx -o result.xlsx

Specify the output name:

excelsior-data-converter export employees.json --to xlsx -n employees

The import service currently handles:

• XLSX
• XLSM
• XLSB
• XLS
• XLA
• XLAM
• CSV
• JSON

Other formats may be handled as JSON depending on the input data.

The export service supports a wide range of formats, including:

• XLSX
• XLSM
• XLSB
• XLS
• XLA
• XLAM
• Numbers
• ODS
• FODS
• WK1
• WK3
• BIFF2
• BIFF3
• BIFF4
• BIFF5

• CSV
• TSV
• TXT
• HTML
• RTF
• PRN
• SYLK
• DIF
• DBF
• ETH

• PDF
• DOCX
• DOC

• PNG
• JPEG
• BMP
• GIF
• TIFF

• SVG
• XML
• JSON

import {
  ImportService,
  ExportService
} from '@unsonet/excelsior-data-converter';

const importer = new ImportService();
const exporter = new ExportService();

The library is designed to work in modern browsers and can be used in browser applications and browser extensions.

All browser-side processing is performed locally.

import {
  ImportService,
  ExportService
} from '@unsonet/excelsior-data-converter';

const importer = new ImportService();
const exporter = new ExportService();

Node.js 18+ is recommended.

The package also provides a command-line interface for Node.js.

The package includes TypeScript declarations.

import { ExportService } from '@unsonet/excelsior-data-converter';

const service = new ExportService();

await service.download(
  [
    { id: 1, name: 'John' },
    { id: 2, name: 'Alice' }
  ],
  'employees',
  'xlsx'
);

No additional type definitions are required.

Excelsior Data Converter can be used for:

• Browser extensions
• Data migration
• ETL workflows
• Spreadsheet processing
• Client-side data conversion
• Server-side data conversion
• Exporting application data
• Converting spreadsheet data to JSON
• Converting JSON data to spreadsheet formats

The library does not provide:

• OCR
• Scanned document recognition
• Image-based table extraction
• AI-assisted data extraction

MIT