you can try this

by burningbon - 5/12/13 7:44 PM

In Reply to: PDF Merge/Split for .NET by fchivu

of course you can't find it because there is merely no free sdks on the internet nowadays. if you haven't found a good tool , you can try this sdk i am currently using which can merge mutiple pdf files into one, good luck . you can follow the steps as follow:

public static void MergePDFDocumentsDemo()
string fileName1 = FolderName + "Sample1.pdf";
string fileName2 = FolderName + "Sample2.pdf";
string fileNameMerged = FolderName + "Merged.pdf";

REDocument doc1 = REFile.OpenDocumentFile(fileName1, new PDFDecoder());//use PDFDecoder open one pdf file
REDocument doc2 = REFile.OpenDocumentFile(fileName2, new PDFDecoder());//use PDFDecoder open another pdf file

BaseDocument docMerged = doc1.MergeDocument(doc2);//merge two pdf

REFile.SaveDocumentFile((REDocument)docMerged, fileNameMerged, new PDFEncoder());//save new pdf