unpdf

unpdf

A collection of utilities for PDF extraction and rendering. Designed specifically for serverless environments, but it also works in Node.js, Deno, Bun and the browser. unpdf is particularly useful for serverless AI applications, especially for summarizing PDF documents in document analysis workflows.

This library ships with a serverless build/redistribution of Mozilla's PDF.js that is optimized for edge environments. Some string replacements, global mocks and inlining the PDF.js worker allow the browser code to become platform agnostic. See pdfjs.rollup.config.ts for the details.

This library is also intended as a modern alternative to the unmaintained but still popular pdf-parse.

Features

• 🏗️ Made for Node.js, browser and serverless environments
• 🪭 Includes serverless build of PDF.js (unpdf/pdfjs)
• 💬 Extract text, links, and images from PDF files
• 🧠 Perfect for AI applications and PDF summarization
• 🧱 Opt-in to legacy PDF.js build
• 💨 Zero dependencies

PDF.js Compatibility

[!Tip] The serverless PDF.js bundle provided by unpdf is built from PDF.js v5.4.296.

You can use an official PDF.js build by using the definePDFJSModule method. This is useful if you want to use a specific version or a custom build of PDF.js.

Installation

Run the following command to add unpdf to your project.

# pnpm
pnpm add -D unpdf

# npm
npm install -D unpdf

# yarn
yarn add -D unpdf

Usage

Extract Text From PDF

import { extractText, getDocumentProxy } from 'unpdf'

// Either fetch a PDF file from the web or load it from the file system
const buffer = await fetch('https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf')
  .then(res => res.arrayBuffer())
const buffer = await readFile('./dummy.pdf')

// Then, load the PDF file into a PDF.js document
const pdf = await getDocumentProxy(new Uint8Array(buffer))

// Finally, extract the text from the PDF file
const { totalPages, text } = await extractText(pdf, { mergePages: true })

console.log(`Total pages: ${totalPages}`)
console.log(text)

Official or Legacy PDF.js Build

Usually you don't need to worry about the PDF.js build. unpdf ships with a serverless build of the latest PDF.js version. However, if you want to use the official PDF.js version or the legacy build, you can define a custom PDF.js module.

[!WARNING] PDF.js v5.x uses Promise.withResolvers, which may not be supported in all environments, such as Node < 22. Consider to use the bundled serverless build, which includes a polyfill, or use an older version of PDF.js.

For example, if you want to use the official PDF.js build, you can do the following:

import { definePDFJSModule, extractText, getDocumentProxy } from 'unpdf'

// Define the PDF.js build before using any other unpdf method
await definePDFJSModule(() => import('pdfjs-dist'))

// Now, you can use all unpdf methods with the official PDF.js build
const pdf = await getDocumentProxy(/* … */)
const { text } = await extractText(pdf)

PDF.js API

unpdf provides helpful methods to work with PDF files, such as extractText and extractImages, which should cover most use cases. However, if you need more control over the PDF.js API, you can use the getResolvedPDFJS method to get the resolved PDF.js module.

Access the PDF.js API directly by calling getResolvedPDFJS:

import { getResolvedPDFJS } from 'unpdf'

const { version } = await getResolvedPDFJS()

[!NOTE] If no other PDF.js build was defined, the serverless build will always be used.

For example, you can use the getDocument method to load a PDF file and then use the getMetadata method to get the metadata of the PDF file:

import { readFile } from 'node:fs/promises'
import { getResolvedPDFJS } from 'unpdf'

const { getDocument } = await getResolvedPDFJS()
const data = await readFile('./dummy.pdf')
const document = await getDocument(new Uint8Array(data)).promise

console.log(await document.getMetadata())

API

definePDFJSModule

Allows to define a custom PDF.js build. This method should be called before using any other method. If no custom build is defined, the serverless build will be used.

Type Declaration

function definePDFJSModule(pdfjs: () => Promise<PDFJS>): Promise<void>

getResolvedPDFJS

Returns the resolved PDF.js module. If no other PDF.js build was defined, the serverless build will be used. This method is useful if you want to use the PDF.js API directly.

Type Declaration

function getResolvedPDFJS(): Promise<PDFJS>

getMeta

Extracts metadata from a PDF. If parseDates is set to true, the date properties will be parsed into Date objects.

Type Declaration

function getMeta(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  options?: {
    parseDates?: boolean
  },
): Promise<{
  info: Record<string, any>
  metadata: Record<string, any>
}>

extractText

Extracts all text from a PDF. If mergePages is set to true, the text of all pages will be merged into a single string. Otherwise, an array of strings for each page will be returned.

Type Declaration

function extractText(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  options?: {
    mergePages?: false
  }
): Promise<{
  totalPages: number
  text: string[]
}>
function extractText(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  options: {
    mergePages: true
  }
): Promise<{
  totalPages: number
  text: string
}>

extractLinks

Extracts all links from a PDF document, including hyperlinks and external URLs.

Type Declaration

function extractLinks(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
): Promise<{
  totalPages: number
  links: string[]
}>

Example

import { readFile } from 'node:fs/promises'
import { extractLinks, getDocumentProxy } from 'unpdf'

// Load a PDF file
const buffer = await readFile('./document.pdf')
const pdf = await getDocumentProxy(new Uint8Array(buffer))

// Extract all links from the PDF
const { totalPages, links } = await extractLinks(pdf)

console.log(`Total pages: ${totalPages}`)
console.log(`Found ${links.length} links:`)
for (const link of links) console.log(link)

extractImages

Extracts images from a specific page of a PDF document, including necessary metadata such as width, height, and calculated color channels.

[!NOTE] This method will only work in Node.js and browser environments.

In order to use this method, make sure to meet the following requirements:

• Use the official PDF.js build (see below for details).
• Install the @napi-rs/canvas package if you are using Node.js. This package is required to render the PDF page as an image.

Type Declaration

interface ExtractedImageObject {
  data: Uint8ClampedArray
  width: number
  height: number
  channels: 1 | 3 | 4
  key: string
}

function extractImages(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  pageNumber: number,
): Promise<ExtractedImageObject[]>

Example

[!NOTE] The following example uses the sharp library to process and save the extracted images. You will need to install it with your preferred package manager.

import { readFile, writeFile } from 'node:fs/promises'
import sharp from 'sharp'
import { extractImages, getDocumentProxy } from 'unpdf'

async function extractPdfImages() {
  const buffer = await readFile('./document.pdf')
  const pdf = await getDocumentProxy(new Uint8Array(buffer))

  // Extract images from page 1
  const imagesData = await extractImages(pdf, 1)
  console.log(`Found ${imagesData.length} images on page 1`)

  // Process each image with sharp (optional)
  let totalImagesProcessed = 0
  for (const imgData of imagesData) {
    const imageIndex = ++totalImagesProcessed

    await sharp(imgData.data, {
      raw: {
        width: imgData.width,
        height: imgData.height,
        channels: imgData.channels
      }
    })
      .png()
      .toFile(`image-${imageIndex}.png`)

    console.log(`Saved image ${imageIndex} (${imgData.width}x${imgData.height}, ${imgData.channels} channels)`)
  }
}

extractPdfImages().catch(console.error)

renderPageAsImage

To render a PDF page as an image, you can use the renderPageAsImage method. This method will return an ArrayBuffer of the rendered image. It can also return a data URL (string) if toDataURL option is set to true.

[!NOTE] This method will only work in Node.js and browser environments.

In order to use this method, make sure to meet the following requirements:

• Use the official PDF.js build (see below for details).
• Install the @napi-rs/canvas package if you are using Node.js. This package is required to render the PDF page as an image.

Type Declaration

function renderPageAsImage(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  pageNumber: number,
  options?: {
    canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
    /** @default 1.0 */
    scale?: number
    width?: number
    height?: number
    toDataURL?: false
  },
): Promise<ArrayBuffer>
function renderPageAsImage(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  pageNumber: number,
  options: {
    canvasImport?: () => Promise<typeof import('@napi-rs/canvas')>
    /** @default 1.0 */
    scale?: number
    width?: number
    height?: number
    toDataURL: true
  },
): Promise<string>

Examples

import { definePDFJSModule, renderPageAsImage } from 'unpdf'

// Use the official PDF.js build
await definePDFJSModule(() => import('pdfjs-dist'))

const pdf = await readFile('./dummy.pdf')
const buffer = new Uint8Array(pdf)
const pageNumber = 1

const result = await renderPageAsImage(buffer, pageNumber, {
  canvasImport: () => import('@napi-rs/canvas'),
  scale: 2,
})
await writeFile('dummy-page-1.png', new Uint8Array(result))

import { definePDFJSModule, renderPageAsImage } from 'unpdf'

await definePDFJSModule(() => import('pdfjs-dist'))

const pdf = await readFile('./dummy.pdf')
const buffer = new Uint8Array(pdf)
const pageNumber = 1

const result = await renderPageAsImage(buffer, pageNumber, {
  canvasImport: () => import('@napi-rs/canvas'),
  scale: 2,
  toDataURL: true,
})

const html = `<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Dummy Page</title>
  </head>
  <body>
    <img alt="Example Page" src="${result}">
  </body>
</html>`

await writeFile('dummy-page-1.html', html)

License

MIT License © 2023-PRESENT Johann Schopplich