Combine two (or more) PDF's

I had to solve a similar problem and what I ended up doing was creating a small pdfmerge utility that uses the PDFSharp project which is essentially MIT licensed.

The code is dead simple, I needed a cmdline utility so I have more code dedicated to parsing the arguments than I do for the PDF merging:

using (PdfDocument one = PdfReader.Open("file1.pdf", PdfDocumentOpenMode.Import))
using (PdfDocument two = PdfReader.Open("file2.pdf", PdfDocumentOpenMode.Import))
using (PdfDocument outPdf = new PdfDocument())
{                
    CopyPages(one, outPdf);
    CopyPages(two, outPdf);

    outPdf.Save("file1and2.pdf");
}

void CopyPages(PdfDocument from, PdfDocument to)
{
    for (int i = 0; i < from.PageCount; i++)
    {
        to.AddPage(from.Pages[i]);
    }
}

PDFsharp seems to allow merging multiple PDF documents into one.

And the same is also possible with ITextSharp.

There's some good answers here already, but I thought I might mention that pdftk might be useful for this task. Instead of producing one PDF directly, you could produce each PDF you need and then combine them together as a post-process with pdftk. This could even be done from within your program using a system() or ShellExecute() call.

You could try pdf-shuffler gtk-apps.org

I know a lot of people have recommended PDF Sharp, however it doesn't look like that project has been updated since june of 2008. Further, source isn't available.

Personally, I've been playing with iTextSharp which has been pretty easy to work with.

Following method merges two pdfs( f1 and f2) using iTextSharp. The second pdf is appended after a specific index of f1.

 string f1 = "D:\\a.pdf";
 string f2 = "D:\\Iso.pdf";
 string outfile = "D:\\c.pdf";
 appendPagesFromPdf(f1, f2, outfile, 3);




  public static void appendPagesFromPdf(String f1,string f2, String destinationFile, int startingindex)
        {
            PdfReader p1 = new PdfReader(f1);
            PdfReader p2 = new PdfReader(f2);
            int l1 = p1.NumberOfPages, l2 = p2.NumberOfPages;


            //Create our destination file
            using (FileStream fs = new FileStream(destinationFile, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                Document doc = new Document();

                PdfWriter w = PdfWriter.GetInstance(doc, fs);
                doc.Open();
                for (int page = 1; page <= startingindex; page++)
                {
                    doc.NewPage();
                    w.DirectContent.AddTemplate(w.GetImportedPage(p1, page), 0, 0);
                    //Used to pull individual pages from our source

                }//  copied pages from first pdf till startingIndex
                for (int i = 1; i <= l2;i++)
                {
                    doc.NewPage();
                    w.DirectContent.AddTemplate(w.GetImportedPage(p2, i), 0, 0);
                }// merges second pdf after startingIndex
                for (int i = startingindex+1; i <= l1;i++)
                {
                    doc.NewPage();
                    w.DirectContent.AddTemplate(w.GetImportedPage(p1, i), 0, 0);
                }// continuing from where we left in pdf1 

                doc.Close();
                p1.Close();
                p2.Close();

            }
        }

To solve a similar problem i used iTextSharp like this:

//Create the document which will contain the combined PDF's
Document document = new Document();

//Create a writer for de document
PdfCopy writer = new PdfCopy(document, new FileStream(OutPutFilePath, FileMode.Create));
if (writer == null)
{
     return;
}

//Open the document
document.Open();

//Get the files you want to combine
string[] filePaths = Directory.GetFiles(DirectoryPathWhereYouHaveYourFiles);
foreach (string filePath in filePaths)
{
     //Read the PDF file
     using (PdfReader reader = new PdfReader(vls_FilePath))
     {
         //Add the file to the combined one
         writer.AddDocument(reader);
     }
}

//Finally close the document and writer
writer.Close();
document.Close();

Here is a link to an example using PDFSharp and ConcatenateDocuments

Here the solution http://www.wacdesigns.com/2008/10/03/merge-pdf-files-using-c It use free open source iTextSharp library http://sourceforge.net/projects/itextsharp

I've done this with PDFBox. I suppose it works similarly to iTextSharp.