TL;DR: Learn six effective ways to merge PDFs in C# using the Syncfusion PDF Library. Streamline your document workflow, batch process files, and combine multiple PDFs seamlessly.
In today’s digital age, PDFs have become the go-to format for sharing, archiving, and managing documents. Whether you’re handling business reports, legal paperwork, or personal files, merging multiple PDFs into one cohesive file is often essential. Doing so simplifies organization, enhances consistency, and makes it easier to share documents professionally.
With the Syncfusion PDF Library, merging PDF files is straightforward and can be automated for batch processes, saving time and effort.
This blog will cover the following six efficient methods to merge PDF files:
Let’s get started!
Install-Package Syncfusion.Pdf.Net.Core
Combining multiple PDF documents into a single file is a common task, especially when consolidating reports, forms, or other documents into one unified PDF. This process can be accomplished using the Syncfusion PDF Library with just a few lines of code.
In this example, we’ll merge the following two PDF files, file1.pdf, and file2.pdf, located in the project’s data folder.
file1.pdf
Refer to the following code example.
using Syncfusion.Pdf;
//Create a PDF document.
using (PdfDocument finalDocument = new PdfDocument())
{
//Get the stream from an existing PDF document.
using (FileStream firstStream = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read))
using (FileStream secondStream = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read))
{
//Create a stream array for merging.
Stream[] streams = { firstStream, secondStream };
//Merge PDF documents.
PdfDocumentBase.Merge(finalDocument, streams);
//Save the document.
using (FileStream outputStream = new FileStream("combine-multiple-pdf-files.pdf", FileMode.Create, FileAccess.ReadWrite))
{
finalDocument.Save(outputStream);
}
}
} When you execute the above code example, you’ll obtain a single merged PDF document as the output.
Merging selected page ranges from different PDF documents involves combining specific pages from multiple PDFs into one file. You can easily achieve this using the Syncfusion PDF library by loading each PDF, selecting the desired page ranges, and appending these pages to a new document. This allows precise control over the pages that need to be included in the final merged PDF.
In this example, we’ll take pages 2 to 5 from file1.pdf and pages 1 to 2 from file2.pdf to merge these specific pages into a single PDF file.
file1.pdf
// Create a new PDF document.
using PdfDocument finalDocument = new PdfDocument();
// Open and load the first PDF file.
using FileStream firstStream = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read);
PdfLoadedDocument loadedDocument1 = new PdfLoadedDocument(firstStream);
// Import pages 2 to 5 from the first PDF document.
finalDocument.ImportPageRange(loadedDocument1, 1, 5);
// Open and load the second PDF file.
using FileStream secondStream = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read);
PdfLoadedDocument loadedDocument2 = new PdfLoadedDocument(secondStream);
// Import pages 1 to 2 from the second PDF document.
finalDocument.ImportPageRange(loadedDocument2, 0, 1);
// Save the final document.
using FileStream outputStream = new FileStream("merge-selected-page-ranges.pdf", FileMode.Create, FileAccess.ReadWrite);
finalDocument.Save(outputStream); After running the program, you will get a PDF file containing the merged page ranges from both input documents.
Optimizing resources during the PDF merging process involves reducing file size and memory usage while maintaining the quality of the merged document. With the Syncfusion PDF Library, you can streamline the merging process by efficiently managing resources such as images, fonts, and other assets, ensuring that the resulting PDF is compact and optimized for performance.
The OptimizeResources property in PdfMergeOptions is used to optimize PDF page resources during the merging process.
// Create a new PDF document.
using (PdfDocument outputDocument = new PdfDocument())
{
// Load the first PDF document.
using (FileStream firstPDFStream = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read))
{
// Load the second PDF document
using (FileStream secondPDFStream = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read))
{
// Create a list of streams to merge.
Stream[] streams = { firstPDFStream, secondPDFStream };
// Create a merge options object.
PdfMergeOptions mergeOptions = new PdfMergeOptions();
// Enable the optimize resources option.
mergeOptions.OptimizeResources = true;
// Merge the PDF documents with optimization.
PdfDocumentBase.Merge(outputDocument, mergeOptions, streams);
// Save the document.
using (FileStream outputMemoryStream = new FileStream("optimize-resources-merge-pdf.pdf", FileMode.Create, FileAccess.ReadWrite))
{
outputDocument.Save(outputMemoryStream);
}
}
}
} After running the code, you will receive a merged PDF file optimized for size, ensuring efficient resource usage.
Note: The optimization process is most effective when the PDF documents being merged contain identical resources, such as fonts, images, and other embedded elements. The optimization may not significantly reduce the file size if the resources differ between the PDFs.
Extending the page margins while merging PDF documents allows you to add additional space around the content of each page in the final merged document. Using the Syncfusion PDF Library, you can adjust the page layout during the merging process, ensuring that the merged PDF has consistent and expanded margins as needed.
// Create a new PDF document with 50-point margins.
using PdfDocument outputDocument = new PdfDocument
{
PageSettings = { Margins = { All = 50 } }
};
// Load the first and second PDF documents.
using FileStream firstPDFStream = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read);
using FileStream secondPDFStream = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read);
// Create a merge options object and enable the margin extension.
PdfMergeOptions mergeOptions = new PdfMergeOptions
{
ExtendMargin = true
};
// Merge the PDF documents with extended margins.
PdfDocumentBase.Merge(outputDocument, mergeOptions, new[] { firstPDFStream, secondPDFStream });
// Save the document with extended margins.
using FileStream outputMemoryStream = new FileStream("extend-margins-while-merging-pdfs.pdf", FileMode.Create, FileAccess.ReadWrite);
outputDocument.Save(outputMemoryStream); After running the program, you will obtain a merged PDF with extended margins on each page, providing consistent extra space around the content.
Preserving accessibility tags when merging PDF files ensures that the merged document retains important metadata and structure, such as headings, reading order, and alternative text for images. These tags are crucial for making PDFs accessible to users with disabilities, enabling screen readers and other assistive technologies to interpret the content correctly.
Using the Syncfusion PDF Library, you can merge PDF documents while maintaining these accessibility features, ensuring that the resulting file remains fully accessible.
// Create a new PDF document.
using (PdfDocument finalDoc = new PdfDocument())
{
// Load the first and second PDF documents.
using (FileStream stream1 = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read))
using (FileStream stream2 = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read))
{
// Create merge options and enable accessibility tag merging.
PdfMergeOptions mergeOptions = new PdfMergeOptions
{
MergeAccessibilityTags = true
};
// Merge PDF documents with accessibility tags preserved.
PdfDocumentBase.Merge(finalDoc, mergeOptions, new[] { stream1, stream2 });
// Save the merged document with preserved accessibility tags.
using (FileStream outputFileStream = new FileStream("merge-tags.pdf", FileMode.Create, FileAccess.ReadWrite))
{
finalDoc.Save(outputFileStream);
}
}
} After running this program, the resulting merged PDF (merge-tags.pdf) will retain all accessibility features from the original files, ensuring that the document is fully accessible and can be navigated by assistive technologies such as screen readers.
Adding bookmarks to the merged PDF documents enhances navigation by allowing users to jump to specific sections or pages within the document quickly. Bookmarks act as an interactive table of contents, making it easier to locate key content.
Using the Syncfusion PDF Library, users can create bookmarks based on individual file titles. This will help quickly navigate to specific sections of the merged file.
// Create a new PDF document.
using (PdfDocument finalDocument = new PdfDocument())
{
// Load the first and second PDF documents.
using (FileStream firstStream = new FileStream("data/file1.pdf", FileMode.Open, FileAccess.Read))
using (FileStream secondStream = new FileStream("data/file2.pdf", FileMode.Open, FileAccess.Read))
{
// Load the stream into PdfLoadedDocument class.
using PdfLoadedDocument loadedDocument1 = new PdfLoadedDocument(firstStream);
using PdfLoadedDocument loadedDocument2 = new PdfLoadedDocument(secondStream);
// Merge the PDF documents.
PdfDocumentBase.Merge(finalDocument, new[] { loadedDocument1, loadedDocument2 });
// Create a bookmark for the first PDF file.
PdfBookmark bookmark1 = finalDocument.Bookmarks.Add("Chapter 1 - Barcodes");
// Set the destination page for the first bookmark.
bookmark1.Destination = new PdfDestination(finalDocument.Pages[0]);
// Set the location for the first bookmark.
bookmark1.Destination.Location = new PointF(20, 20);
// Create a bookmark for the second PDF file.
PdfBookmark bookmark2 = finalDocument.Bookmarks.Add("Chapter 2 - HTTP Succinctly");
// Set the destination page for the second bookmark (after the pages of the first PDF)
bookmark2.Destination = new PdfDestination(finalDocument.Pages[loadedDocument1.PageCount]);
// Set the location for the second bookmark.
bookmark2.Destination.Location = new PointF(20, 20);
// Save the document with bookmarks into a stream.
using (FileStream outputFileStream = new FileStream("add-bookmarks.pdf", FileMode.Create, FileAccess.ReadWrite))
{
finalDocument.Save(outputFileStream);
}
}
} When you execute this code, the output will be a merged PDF file named add-bookmarks.pdf. The document will include bookmarks representing each appended PDF, enabling easy navigation through the content using a bookmark panel in the PDF viewer.
For more details, refer to the 6 ways to merge PDF files using the .NET PDF Library and C# GitHub demo.
Thank you for reading! In this blog, we’ve explored how to merge PDF files using the Syncfusion .NET PDF Library in C#. We encourage you to dive deeper into the documentation, where you’ll find even more options and features, complete with code examples.
If you have any queries regarding these functionalities, kindly let us know by leaving a comment below. You can also reach out to us through our support forum, support portal, or feedback portal. We are always delighted to help you!