New PDF Document API: Merge and Split Files

• Jul 20, 2026
• 2 minutes to read

The new PDF Document API allows you to merge multiple PDFs into a single file and split a PDF into multiple files.

Merge PDF Files

Run Demo: Merge and Split PDF Files

Merge Entire Documents

Call the PdfDocument.AppendDocument to merge PDF files.

The following code snippet merges three PDF files into a single document:

C#

using DevExpress.Docs.Pdf;

using var pdfDocument = new PdfDocument(File.OpenRead("Document.pdf"));

pdfDocument.AppendDocument(File.OpenRead("Document2.pdf"));
pdfDocument.AppendDocument(File.OpenRead("Document3.pdf"));

using var outputStream = new MemoryStream();
pdfDocument.Save(outputStream);

VB.NET

Imports DevExpress.Docs.Pdf

Using pdfDocument As New PdfDocument(File.OpenRead("Document.pdf"))
    pdfDocument.AppendDocument(File.OpenRead("Document2.pdf"))
    pdfDocument.AppendDocument(File.OpenRead("Document3.pdf"))

    Using outputStream As New MemoryStream()
    pdfDocument.Save(outputStream)
    End Using
End Using

The LoadOptions class allows you to specify a metadata synchronization mode and a password for an encrypted document. Pass a LoadOptions instance to the PdfDocument.AppendDocument method to apply these settings when you merge PDF files.

Append Individual Pages

Pass the page you want to append from the source document to the PdfDocument.Pages.Add method. The method adds the page to the end of the target document.

To add a page at a specific position, use the PdfDocument.Pages.Insert method.

The following code snippet appends the first page from one PDF document to another:

C#

using DevExpress.Docs.Pdf;

using (var source = new PdfDocument(File.OpenRead("Document.pdf")))
{
    using (var output = new PdfDocument())
    {
        output.Pages.Append(source.Pages[0]);


        using (var outputStream = new FileStream("Document_1.pdf", FileMode.OpenOrCreate, FileAccess.ReadWrite))
        {
            output.Save(outputStream);
            outputStream.Position = 0;
        }
    }
}

VB.NET

Imports DevExpress.Docs.Pdf

Using source As New PdfDocument(File.OpenRead("Document.pdf"))
    Using output As New PdfDocument()
        output.Pages.Append(source.Pages(0))

        Using outputStream As New FileStream("Document_1.pdf", FileMode.OpenOrCreate, FileAccess.ReadWrite)
            output.Save(outputStream)
            outputStream.Position = 0
        End Using
    End Using
End Using

Split PDF Files

Run Demo: Merge and Split PDF Files

To split a PDF file, clone the required pages from the source document and insert them into a new PdfDocument instance.

The following code snippet splits a PDF file into two separate documents:

C#

using DevExpress.Docs.Pdf;

using var source = new PdfDocument(File.OpenRead("Document.pdf"));

var pageRange = Enumerable.Range(0, source.Pages.Count / 2);
using var output = new PdfDocument();

foreach (var index in pageRange)
{
    output.Pages.Add(source.Pages[index].Clone());
}
using (var outputStream = new FileStream("Document_1.pdf", FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
    output.Save(outputStream);
    outputStream.Position = 0;
}

VB.NET

Imports DevExpress.Docs.Pdf

Using source As New PdfDocument(File.OpenRead("Document.pdf"))

    Dim pageRange = Enumerable.Range(0, source.Pages.Count / 2)
    Using output As New PdfDocument()

        For Each index In pageRange
            output.Pages.Add(source.Pages(index).Clone())
        Next
        Using outputStream As New FileStream("Document_1.pdf", FileMode.OpenOrCreate, FileAccess.ReadWrite)
            output.Save(outputStream)
            outputStream.Position = 0
    End Using
  End Using
End Using