Combine PDF in memory with C# and .NET

Combining PDF files in memory is a powerful feature that can be easily implemented in C# using the SautinSoft.Pdf .Net library. This approach is effective and safe because it does not require writing intermediate files to disk. Regardless of whether you are working with a desktop, web, or cloud application, this method makes it easy to combine PDF documents programmatically. This can be especially useful when creating a single document from multiple reports or receipts.

To merge PDF files in memory using C# and .NET, follow these steps:

  1. Add SautinSoft.PDF from NuGet.
  2. Read PDF files to a Memory.
  3. Merge PDF documents using MemoryStream.
  4. Save the document to show the result.

Output result:

Complete code

using System;
using System.IO;
using System.Collections.Generic;
using SautinSoft;
using SautinSoft.Pdf;
using SautinSoft.Pdf.Content;
using SautinSoft.Pdf.Facades;

namespace Sample
{
    class Sample
    {
        /// <summary>
        /// Merge PDF documents in memory using C# and .NET.
        /// </summary>
        /// <remarks>
        /// Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/merge-pdf-documents-in-memory-using-csharp-and-dotnet.php
        /// </remarks>
        static void Main(string[] args)
        {
            // Before starting this example, please get a free 100-day trial key:
            // https://sautinsoft.com/start-for-free/

            // Apply the key here:
            // PdfDocument.SetLicense("...");

            MergePdfInMemory();
        }
        static void MergePdfInMemory()
        {
            // In this example we are using files only to get input data and show the result.
            string resultPath = "Result.pdf";
            // The whole merge process will be done completely in memory. 

            // The list with PDFs. The each document stored as bytes array.
            List<byte[]> pdfDocs = new List<byte[]>();
            foreach (var f in Directory.GetFiles(@"..\..\..\", "*.pdf"))
                pdfDocs.Add(File.ReadAllBytes(f));

            // Create a PDF merger.
            var merger = new PdfMerger();

            // Iterate by documents and append them.
            foreach (var pdfDoc in pdfDocs)
                using (var ms = new MemoryStream(pdfDoc))
                    merger.Append(ms);

            // Save the merged PDF to a MemoryStream.
            using (var msMerged = new MemoryStream())
            {
                merger.Save(msMerged);
                // Save the result to a file to show.
                File.WriteAllBytes(resultPath, msMerged.ToArray());
            }

            // Show the result.
            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(resultPath) { UseShellExecute = true });
        }
    }
}

Download

In the example above, you can see that the source PDF file is combined and the pages cloned into a new PDF.Net, which is then saved to a PDF file.

If you need a new code example or have a question: email us at support@sautinsoft.com or ask at Online Chat (right-bottom corner of this page) or use the Form below:


Questions and suggestions from you are always welcome!

We are developing .Net components since 2002. We know PDF, DOCX, RTF, HTML, XLSX and Images formats. If you need any assistance with creating, modifying or converting documents in various formats, we can help you. We will write any code example for you absolutely free.