How to Add and Remove PDF Attachments in C# with IronPDF

What File Types Can I Attach to a PDF?

IronPDF supports attaching virtually any file type to PDF documents. Common attachment types include:

• Office documents (DOCX, XLSX, PPTX)
• Images (JPG, PNG, GIF, SVG)
• Text files (TXT, CSV, XML)
• Archives (ZIP, RAR)
• Other PDFs

The attachment system works with binary data, so any file that can be read as bytes can be attached. When working with specific document types, you might also consider IronPDF's built-in conversion features, such as converting DOCX to PDF or converting images to PDF.

Where Do Attachments Appear in PDF Viewers?

Different PDF viewers display attachments in various locations:

• Adobe Acrobat: Shows a paperclip icon in the navigation pane
• Chrome PDF Viewer: Displays attachments in the left sidebar when clicked
• Firefox PDF Viewer: Shows attachments in a dedicated panel
• Microsoft Edge: Similar to Chrome, with a sidebar attachment view

Most modern PDF viewers support attachments, though the interface may vary slightly between applications.

What Happens to the PdfAttachment Object After Adding?

When you call AddAttachment(), IronPDF creates a PdfAttachment object that contains:

• Name: The display name of the attachment
• Data: The binary content of the attached file
• Description: Optional metadata about the attachment

This object is added to the PDF's internal attachment collection and remains accessible through the Attachments property until explicitly removed.

How Do I Access Multiple Attachments in a PDF?

The Attachments property returns a collection that you can iterate through or query using LINQ:

// Get all attachments as a list
var allAttachments = pdf.Attachments.ToList();

// Filter attachments by size (e.g., files larger than 1MB)
var largeAttachments = pdf.Attachments
    .Where(a => a.Data.Length > 1024 * 1024)
    .ToList();

// Find specific attachment by exact name
var specificAttachment = pdf.Attachments
    .FirstOrDefault(a => a.Name == "report.xlsx");

// Get all attachments as a list
var allAttachments = pdf.Attachments.ToList();

// Filter attachments by size (e.g., files larger than 1MB)
var largeAttachments = pdf.Attachments
    .Where(a => a.Data.Length > 1024 * 1024)
    .ToList();

// Find specific attachment by exact name
var specificAttachment = pdf.Attachments
    .FirstOrDefault(a => a.Name == "report.xlsx");

What Properties Are Available on Retrieved Attachments?

Each PdfAttachment object provides:

• Name: The display name of the attachment
• Data: Binary content as byte array
• Description: Optional description metadata (if set)

You can use these properties to identify, filter, and process attachments based on your requirements.

How Can I Filter Attachments by Name or Type?

Since attachments are stored with their display names, you can filter them using string operations:

// Filter by file extension (assuming names include extensions)
var imageAttachments = pdf.Attachments
    .Where(a => a.Name.EndsWith(".jpg") || 
                a.Name.EndsWith(".png") || 
                a.Name.EndsWith(".gif"))
    .ToList();

// Filter by name pattern
var reportsOnly = pdf.Attachments
    .Where(a => a.Name.StartsWith("Report_"))
    .ToList();

// Filter by file extension (assuming names include extensions)
var imageAttachments = pdf.Attachments
    .Where(a => a.Name.EndsWith(".jpg") || 
                a.Name.EndsWith(".png") || 
                a.Name.EndsWith(".gif"))
    .ToList();

// Filter by name pattern
var reportsOnly = pdf.Attachments
    .Where(a => a.Name.StartsWith("Report_"))
    .ToList();

What Happens When I Remove an Attachment?

When you remove an attachment:

1. The attachment data is completely removed from the PDF file
2. The file size decreases by approximately the size of the removed attachment
3. Any references to that attachment in the PDF structure are cleaned up
4. The change is permanent once you save the PDF

This is similar to other PDF modification operations like removing pages or redacting content.

Can I Remove Multiple Attachments at Once?

Yes, you can remove multiple attachments in a single operation. Here's an example:

// Remove all attachments that match a pattern
var attachmentsToRemove = pdf.Attachments
    .Where(a => a.Name.StartsWith("temp_"))
    .ToList();

foreach (var attachment in attachmentsToRemove)
{
    pdf.Attachments.RemoveAttachment(attachment);
}

// Or remove all attachments at once
while (pdf.Attachments.Count > 0)
{
    pdf.Attachments.RemoveAttachment(pdf.Attachments.First());
}

// Remove all attachments that match a pattern
var attachmentsToRemove = pdf.Attachments
    .Where(a => a.Name.StartsWith("temp_"))
    .ToList();

foreach (var attachment in attachmentsToRemove)
{
    pdf.Attachments.RemoveAttachment(attachment);
}

// Or remove all attachments at once
while (pdf.Attachments.Count > 0)
{
    pdf.Attachments.RemoveAttachment(pdf.Attachments.First());
}

How Do I Verify an Attachment Was Successfully Removed?

You can verify attachment removal in several ways:

// Check the attachment count
int attachmentCountBefore = pdf.Attachments.Count;
pdf.Attachments.RemoveAttachment(targetAttachment);
int attachmentCountAfter = pdf.Attachments.Count;

// Verify the count decreased
if (attachmentCountAfter < attachmentCountBefore)
{
    Console.WriteLine("Attachment successfully removed");
}

// Check if specific attachment exists
bool attachmentExists = pdf.Attachments
    .Any(a => a.Name == "specificFile.txt");

// Check the attachment count
int attachmentCountBefore = pdf.Attachments.Count;
pdf.Attachments.RemoveAttachment(targetAttachment);
int attachmentCountAfter = pdf.Attachments.Count;

// Verify the count decreased
if (attachmentCountAfter < attachmentCountBefore)
{
    Console.WriteLine("Attachment successfully removed");
}

// Check if specific attachment exists
bool attachmentExists = pdf.Attachments
    .Any(a => a.Name == "specificFile.txt");