Description

This node.js library can merge multiple PDF documents, or parts of them, to one new PDF document. You can do this by using the command line interface or from within your node.js or even directly in the browser.

The only dependency is pdf-lib so it can run in any javascript-only environment without any non-javascript dependencies.

Legacy notes

• If you are searching for the legacy version based on pdfjs please install a v3 release. Since v4 we use pdf-lib instead.
• If you are searching for a legacy version using CommonJS modules please install a v4 release. Since v5 we use the modern ESM ("import") instead of the CommonJS ("require) module standard.

Installation

npm install --save pdf-merger-js

or simply do a global installation if you just want to use the cli tool:

npm install -g pdf-merger-js

Usage

CLI "pdf-merge"

Usage: pdf-merge [options] <inputFiles...>

merge multiple PDF documents, or parts of them, to a new PDF document

Options:
  -V, --version              output the version number
  -o, --output <outputFile>  Merged PDF output file path
  -v, --verbose              Print verbose output
  -s, --silent               do not print any output to stdout. Overwrites --verbose
  -h, --help                 display help for command

Example calls

Merge pages 1-2 from the first input with pages 1,2 and 5-7 from the second pdf document:

pdf-merge --output ./merged.pdf ./input1.pdf#1-2 ./input2.pdf#1,2,5-7

Get two pdf files from the an url and merge the first one with pages 2-3 from the second one:

pdf-merge --verbose --output ./sample.pdf Testfile.pdf https://pdfobject.com/pdf/sample.pdf https://upload.wikimedia.org/wikipedia/commons/1/13/Example.pdf#2-3

node.js

The node.js version has the following export functions:

• saveAsBuffer exports a merged pdf as an Buffer.
• save saves the pdf under the given filename.
• setMetadata set Metadata for producer, author, title or creator.
• reset resets the internal state of the document, to start again.

async node.js example

import PDFMerger from 'pdf-merger-js';

var merger = new PDFMerger();

(async () => {
  await merger.add('pdf1.pdf');  //merge all pages. parameter is the path to file and filename.
  await merger.add('pdf2.pdf', 2); // merge only page 2
  await merger.add('pdf2.pdf', [1, 3]); // merge the pages 1 and 3
  await merger.add('pdf2.pdf', '4, 7, 8'); // merge the pages 4, 7 and 8
  await merger.add('pdf3.pdf', '3 to 5'); //merge pages 3 to 5 (3,4,5)
  await merger.add('pdf3.pdf', '3-5'); //merge pages 3 to 5 (3,4,5)

  // Set metadata
  await merger.setMetadata({
    producer: "pdf-merger-js based script",
    author: "John Doe",
    creator: "John Doe",
    title: "My live as John Doe"
  });

  await merger.save('merged.pdf'); //save under given name and reset the internal document
  
  // Export the merged PDF as a nodejs Buffer
  // const mergedPdfBuffer = await merger.saveAsBuffer();
  // fs.writeSync('merged.pdf', mergedPdfBuffer);
})();

Browser

The Browser version has the following export functions:

• saveAsBuffer exports a merged pdf as an Uint8Array.
• saveAsBlob exports a merged pdf as a Blob.
• save starts a file-download directly in the browser.
• setMetadata set Metadata for producer, author, title or creator.
• reset resets the internal state of the document, to start again.

async react example

import PDFMerger from 'pdf-merger-js/browser';
import React, { useEffect, useState } from 'react';

// files: Array of PDF File or Blob objects
const Merger = (files) => {
  const [mergedPdfUrl, setMergedPdfUrl] = useState();

  useEffect(() => {
    const render = async () => {
      const merger = new PDFMerger();

      for(const file of files) {
        await merger.add(file);
      }

      await merger.setMetadata({
        producer: "pdf-merger-js based script"
      });

      const mergedPdf = await merger.saveAsBlob();
      const url = URL.createObjectURL(mergedPdf);

      return setMergedPdfUrl(url);
    };

    render().catch((err) => {
      throw err;
    });

    () => setMergedPdfUrl({});
  }, [files, setMergedPdfUrl]);

  return !data ? (
    <>Loading</>
  ) : (
    <iframe
      height={1000}
      src={`${mergedPdfUrl}`}
      title='pdf-viewer'
      width='100%s'
    ></iframe>
  );
};

Similar libraries

• This library is inspired by the PHP library PDFMerger and has a very similar API.
• pdf-merge has a dependency on PDFtk.
• easy-pdf-merge has a dependency on the Apache PDFBox® - A Java PDF Library.
• pdfmerge has a dependency on python and PyPDF2.