GroupDocs.Merger

using System;
using GroupDocs.Merger;

// Open the source PDF file
using (Merger merger = new Merger(@"c:\sample1.pdf"))
{
  // Append another PDF file for merging
  merger.Join(@"c:\sample2.pdf");

  // Combine PDF files and save the output
  merger.Save(@"c:\merged.pdf");
}

import com.groupdocs.merger.*;

// Load the source PDF file
Merger merger = new Merger("sample1.pdf");

// Add another PDF file to combine
merger.join("sample2.pdf");

// Merge PDF files and save the output
merger.save("merged.pdf");

const groupdocs = require('@groupdocs/groupdocs.merger');

// Load the source PDF file
const merger = new groupdocs.Merger("sample1.pdf");

// Add another PDF file to combine
merger.join("sample2.pdf");

// Merge the PDF files and save the output
merger.save("merged.pdf");
merger.close();

from groupdocs.merger import Merger

def run():

    # Load the original PDF file
    with Merger("sample1.pdf") as merger:

        # Add another PDF file for merging
        merger.join("sample2.pdf")

        # Combine the PDF files and save the output
        merger.save("merged.pdf")