IronPDF can combine the contents of multiple PDF documents. A common use for this feature is in attaching cover pages to new or existing PDFs. Other possible uses include bundling related documents together into one file for convenient printing and transport.

The code example above uses the PdfDocument.merge method on two PdfDocument objects that were both rendered from HTML markup. The result of the invocation is a new PdfDocument produced by appending the content of the latter PdfDocument to the end of the former one.

To combine more than three PDF documents, first create a list containing the required PdfDocument objects, and then pass the list as a single argument to the PdfDocument.merge method:

List<PdfDocument>pdfs = new ArrayList<>();
pdfs.add(pdfA);
pdfs.add(pdfB);
pdf.add(pdfC);
pdf.add(pdfD);
PdfDocument merged = PdfDocument.merge(pdfs);

List<PdfDocument>pdfs = new ArrayList<>();
pdfs.add(pdfA);
pdfs.add(pdfB);
pdf.add(pdfC);
pdf.add(pdfD);
PdfDocument merged = PdfDocument.merge(pdfs);