WebAssembly (WASM) API Usage

The @cle-does-things/pdfitdown-wasm package lets you run PdfItDown directly in the browser through WebAssembly. It is built from the pdfitdown-wasm Rust crate using wasm-bindgen and wasm-pack.

Installation

Via npm

npm install @cle-does-things/pdfitdown-wasm

Via CDN (esm)

<script type="module">
  import init, {
      convert,
  } from "https://unpkg.com/@cle-does-things/pdfitdown-wasm@4.1.0/pkg/pdfitdown_wasm.js";
  await init(
      "https://unpkg.com/@cle-does-things/pdfitdown-wasm@4.1.0/pkg/pdfitdown_wasm_bg.wasm",
  );
  // ... use convert()
</script>

Supported Formats

Category	Formats
Markup	`.md`, `.html`, `.htm`
Office	`.docx`, `.xlsx`, `.pptx`
Images	`.png`, `.jpg`, `.jpeg`, `.webp`, `.tiff`, `.avif`
Text	`.txt`, `.csv`, `.xml`, `.json`, and more
Other	`.pdf` (pass-through)

API

All functions accept a Uint8Array of input bytes and return a Uint8Array of PDF bytes.

General conversion

import init, { convert } from '@cle-does-things/pdfitdown-wasm';

await init();

const inputBytes = new Uint8Array(/* ... */);
const pdfBytes = convert(inputBytes);

Specialized converters

If you already know the file type, you can call a dedicated converter for a slightly smaller WASM footprint:

import init, {
  convertImage,
  convertMarkup,
  convertOffice,
  convertText
} from '@cle-does-things/pdfitdown-wasm';

await init();

const imagePdf = convertImage(imageBytes);
const markupPdf = convertMarkup(markdownBytes);
const officePdf = convertOffice(docxBytes);
const textPdf = convertText(txtBytes);

Browser example

<!DOCTYPE html>
<html>
<head>
  <title>PdfItDown WASM Demo</title>
</head>
<body>
  <input type="file" id="fileInput" />
  <a id="download" style="display:none">Download PDF</a>

  <script type="module">
    import init, {
        convert,
    } from "https://unpkg.com/@cle-does-things/pdfitdown-wasm@4.1.0/pkg/pdfitdown_wasm.js";

    await init(
        "https://unpkg.com/@cle-does-things/pdfitdown-wasm@4.1.0/pkg/pdfitdown_wasm_bg.wasm",
    );

    document.getElementById('fileInput').addEventListener('change', async (e) => {
      const file = e.target.files[0];
      const bytes = new Uint8Array(await file.arrayBuffer());
      const pdfBytes = convert(bytes);

      const blob = new Blob([pdfBytes], { type: 'application/pdf' });
      const url = URL.createObjectURL(blob);

      const link = document.getElementById('download');
      link.href = url;
      link.download = file.name.replace(/\.[^.]+$/, '.pdf');
      link.style.display = 'inline';
      link.textContent = 'Download PDF';
    });
  </script>
</body>
</html>

Find a full browser example here

Edge example

PdfItDown WASM bindings can be used in edge runtimes such as Cloudflare Workers, AWS Lambdas, Vercel Edge Functions and many others. Here is a quick example on how to set up a CloudFlare worker endpoint:

import { convert, initSync } from '@cle-does-things/pdfitdown-wasm';
import wasmModule from '../pdfitdown_wasm_bg.wasm';

let initialized = false;

export default {
	async fetch(request, env, ctx): Promise<Response> {
		if (!initialized) {
			initSync({ module: wasmModule });
			initialized = true;
		}
		const buf = await request.arrayBuffer();
		const converted = convert(new Uint8Array(buf));

		return new Response(converted, {
			headers: { 'Content-Type': 'application/octet-stream' },
		});
	},
} satisfies ExportedHandler<Env>;

Full reference here

Build targets

The package ships three build flavours:

Target	Use case
`web` (default)	Native ES modules in the browser
`bundler`	Webpack, Vite, Rollup, etc.
`nodejs`	Node.js (if you prefer WASM over NAPI-RS)

You can rebuild for a specific target from the monorepo root:

cd packages/wasm
npm run build          # web target
npm run build:bundler  # bundler target
npm run build:nodejs   # nodejs target

​Installation

​Via npm

​Via CDN (esm)

​Supported Formats

​API

​General conversion

​Specialized converters

​Browser example

​Edge example

​Build targets