doc-docx-converter

WASM-powered DOC/DOCX conversion for Node.js.

doc-docx-converter converts older Microsoft Word documents (.doc) and modern Word documents (.docx) into common output formats such as PDF, DOCX, ODT, RTF, TXT, HTML, PNG, JPG, and SVG.

It uses LibreOffice compiled to WebAssembly, so your application does not need a native LibreOffice installation.

Features

• Converts .doc and .docx inputs.
• Outputs pdf, docx, doc, odt, rtf, txt, html, png, jpg, and svg.
• Uses a reusable worker-backed LibreOffice WASM converter for server workloads.
• Provides a one-shot helper for simple scripts.
• Includes TypeScript types.
• Normalizes and validates formats before conversion.
• Supports optional PDF/image settings.

Requirements

• Node.js 18 or newer.
• Enough disk space for the LibreOffice WASM assets.
• Enough memory for LibreOffice WASM initialization and document processing.

No native soffice or LibreOffice installation is required.

Installation

npm install doc-docx-converter

Quick Start

import { convertDocument } from "doc-docx-converter";
import fs from "node:fs";

const input = fs.readFileSync("contract.doc");

const result = await convertDocument(input, {
  inputFormat: "doc",
  outputFormat: "docx",
  filename: "contract.doc"
});

fs.writeFileSync(result.filename, result.data);

Reuse a Converter

For servers and batch jobs, reuse one converter. The first conversion initializes LibreOffice WASM, so reuse is much faster than creating a converter for every file.

import { createDocDocxConverter } from "doc-docx-converter";
import fs from "node:fs";

const converter = await createDocDocxConverter();

try {
  const input = fs.readFileSync("contract.doc");

  const result = await converter.convert(input, {
    inputFormat: "doc",
    outputFormat: "pdf",
    filename: "contract.doc"
  });

  fs.writeFileSync(result.filename, result.data);
} finally {
  await converter.destroy();
}

Express Example

import express from "express";
import multer from "multer";
import { createDocDocxConverter } from "doc-docx-converter";

const app = express();
const upload = multer({
  storage: multer.memoryStorage(),
  limits: {
    fileSize: 20 * 1024 * 1024
  }
});

const converter = await createDocDocxConverter({
  maxInputBytes: 20 * 1024 * 1024
});

app.post("/convert", upload.single("file"), async (req, res, next) => {
  try {
    if (!req.file) {
      res.status(400).json({ message: "Upload a .doc or .docx file." });
      return;
    }

    const result = await converter.convert(req.file.buffer, {
      inputFormat: req.file.originalname.endsWith(".doc") ? "doc" : "docx",
      outputFormat: "pdf",
      filename: req.file.originalname
    });

    res.setHeader("Content-Type", result.mimeType);
    res.setHeader("Content-Disposition", `attachment; filename="${result.filename}"`);
    res.send(Buffer.from(result.data));
  } catch (error) {
    next(error);
  }
});

app.listen(3000);

API

convertDocument(input, options, converterOptions?)

Creates a converter, converts one document, destroys the converter, and returns the result.

Best for scripts, CLIs, and low-volume jobs.

const result = await convertDocument(inputBuffer, {
  inputFormat: "doc",
  outputFormat: "pdf",
  filename: "document.doc"
});

createDocDocxConverter(options?)

Creates a reusable converter.

const converter = await createDocDocxConverter();
const result = await converter.convert(inputBuffer, options);
await converter.destroy();

new DocDocxConverter(options?)

Constructs a converter immediately and starts initialization in the background.

const converter = new DocDocxConverter();
await converter.waitUntilReady();

converter.convert(input, options)

Converts a .doc or .docx document.

const result = await converter.convert(input, {
  inputFormat: "docx",
  outputFormat: "html",
  filename: "proposal.docx"
});

converter.destroy()

Stops the converter worker and releases LibreOffice WASM resources.

Always call this when your script, job, or server is shutting down.

Types

type DocDocxInputFormat = "doc" | "docx";

type DocDocxOutputFormat =
  | "pdf"
  | "docx"
  | "doc"
  | "odt"
  | "rtf"
  | "txt"
  | "html"
  | "png"
  | "jpg"
  | "svg";

interface DocDocxConversionOptions {
  outputFormat: DocDocxOutputFormat;
  inputFormat?: DocDocxInputFormat;
  filename?: string;
  password?: string;
  pdf?: {
    pdfaLevel?: "PDF/A-1b" | "PDF/A-2b" | "PDF/A-3b";
    quality?: number;
  };
  image?: {
    width?: number;
    height?: number;
    dpi?: number;
    pageIndex?: number;
    pages?: number[];
  };
  maxInputBytes?: number;
}

interface DocDocxConversionResult {
  data: Uint8Array;
  mimeType: string;
  filename: string;
  duration: number;
  inputFormat: DocDocxInputFormat;
  outputFormat: DocDocxOutputFormat;
}

PDF Options

const result = await convertDocument(input, {
  inputFormat: "docx",
  outputFormat: "pdf",
  filename: "report.docx",
  pdf: {
    pdfaLevel: "PDF/A-2b",
    quality: 90
  }
});

Image Output

Image outputs render document pages through the LibreOffice WASM engine.

const result = await convertDocument(input, {
  inputFormat: "docx",
  outputFormat: "png",
  filename: "report.docx",
  image: {
    pageIndex: 0,
    dpi: 150
  }
});

Error Handling

Known errors are thrown as DocDocxConverterError.

import { DocDocxConverterError } from "doc-docx-converter";

try {
  await convertDocument(input, {
    inputFormat: "doc",
    outputFormat: "pdf"
  });
} catch (error) {
  if (error instanceof DocDocxConverterError) {
    console.error(error.code, error.message);
  } else {
    console.error(error);
  }
}

Error codes:

• INVALID_INPUT
• UNSUPPORTED_INPUT_FORMAT
• UNSUPPORTED_OUTPUT_FORMAT
• INPUT_TOO_LARGE
• CONVERTER_NOT_READY
• CONVERSION_FAILED

Performance Notes

• The first conversion is slower because LibreOffice WASM must initialize.
• Reuse a converter for servers and batch processing.
• Large .doc files can consume significant memory.
• For API servers, set upload limits and maxInputBytes.
• Run conversions outside request-critical paths if you expect high concurrency.

Security Notes

Documents can be complex untrusted binary inputs. For public upload APIs:

• Enforce file size limits.
• Restrict accepted extensions and MIME types.
• Use authentication/rate limits.
• Run conversion workers with appropriate process isolation for your deployment.
• Do not trust text or HTML extracted from documents without sanitization.

Supported Formats

Input:

• doc
• docx

Output:

• pdf
• docx
• doc
• odt
• rtf
• txt
• html
• png
• jpg
• svg

Build From Source

npm install
npm run typecheck
npm run test
npm run build

License

MIT