PdfEditor API

The unified fluent API for creating and editing PDF documents. Chain metadata, bookmarks, page manipulation, redaction, stamping, encryption, and compression in a single builder.

Three Entry Points

PdfEditor offers three ways to start an editing session. All three return a PdfEditor instance that supports the same chainable methods.

// 1. Open an existing PDF file
PdfEditor.Open("input.pdf")
    .SetTitle("Updated Title")
    .Save("output.pdf");

// 2. Open from in-memory bytes
byte[] pdfBytes = File.ReadAllBytes("input.pdf");
PdfEditor.Open(pdfBytes)
    .SetAuthor("Engineering")
    .Save("output.pdf");

// 3. Generate a new PDF and chain into editing
PdfEditor.Create(doc =>
{
    doc.Page(page =>
    {
        page.Size(PageSizes.A4);
        page.Margin(50);
        page.Content().Text("Fresh document").FontSize(18);
    });
})
.SetTitle("New Document")
.Encrypt(new Encryption256Bit { OwnerPassword = "secret" })
.Save("new-encrypted.pdf");

How It Works: PDFium vs. qpdf

Internally, PdfEditor routes each operation to the correct native backend. You never need to know which backend handles what — the routing is automatic.

Output

End every chain with Save() to write to a file or ToBytes() to get the result as a byte array.

// Save to file
PdfEditor.Open("input.pdf")
    .SetTitle("Report")
    .Save("output.pdf");

// Get bytes (e.g., for HTTP response)
byte[] result = PdfEditor.Open(inputBytes)
    .SetTitle("Report")
    .ToBytes();

// ASP.NET example
var bytes = PdfEditor.Open(templateBytes)
    .SetFormField("name", user.Name)
    .SetFormField("date", DateTime.Now.ToShortDateString())
    .FlattenForm()
    .ToBytes();
return File(bytes, "application/pdf", "filled-form.pdf");

using var editor = PdfEditor.Open("input.pdf");
editor.SetTitle("Updated");
editor.Save("output.pdf");

Complete Method Reference

Metadata

Bookmarks

Page Manipulation

Redaction

Form Fields

Annotations

Drawing

Stamping

Compression

Encryption and Decryption

Linearization

Overlay and Underlay

Attachments

Examples

Post-Process a Generated Report

PdfEditor.Create(doc =>
{
    doc.Page(page =>
    {
        page.Size(PageSizes.A4);
        page.Margin(50);
        page.Header().Text("Q1 Financial Report").FontSize(10);
        page.Content().Column(col =>
        {
            col.Spacing(10);
            col.Item().Text("Revenue Summary").FontSize(20).Bold();
            col.Item().Text("Total revenue: $2.4M (+12% YoY)");
            // ... more content
        });
        page.Footer().AlignCenter().Text(t =>
        {
            t.CurrentPageNumber();
            t.Span(" / ");
            t.TotalPages();
        });
    });
})
.SetTitle("Q1 2026 Financial Report")
.SetAuthor("Finance Department")
.AddBookmark("Revenue Summary", pageIndex: 0)
.StampText(new TextStamp("CONFIDENTIAL")
{
    FontSize = 48,
    Opacity = 0.15f,
    Rotation = -45
})
.Encrypt(new Encryption256Bit
{
    OwnerPassword = "finance-2026",
    AllowPrinting = true,
    AllowContentExtraction = false
})
.Linearize()
.Save("q1-report-final.pdf");

Fill and Flatten a Form Template

var result = PdfEditor.Open("template.pdf")
    .SetFormField("firstName", "Alice")
    .SetFormField("lastName", "Chen")
    .SetFormField("email", "alice@example.com")
    .SetFormField("agreeToTerms", true)
    .FlattenForm()
    .ToBytes();

Merge Multiple Documents

PdfEditor.Open("cover.pdf")
    .MergeFile("chapter1.pdf")
    .MergeFile("chapter2.pdf")
    .AppendDocument(appendixBytes)
    .SetTitle("Complete Manual")
    .AddBookmark("Cover", pageIndex: 0)
    .AddBookmark("Chapter 1", pageIndex: 1)
    .AddBookmark("Chapter 2", pageIndex: 15)
    .Save("manual.pdf");

Redact Sensitive Information

PdfEditor.Open("contract.pdf")
    .RedactText("SSN 123-45-6789")
    .RedactText("Account #9876543210")
    .RedactArea(pageIndex: 2, new RectangleF(50, 600, 200, 30))
    .SetTitle("Redacted Contract")
    .Save("contract-redacted.pdf");

Watermark and Compress

PdfEditor.Open("photos.pdf")
    .StampImage(new ImageStamp(File.ReadAllBytes("watermark.png"))
    {
        Width = 200,
        Opacity = 0.2f,
        HorizontalAlignment = StampAlignment.Center,
        VerticalAlignment = StampAlignment.Center
    })
    .Compress(new CompressionOptions { ImageQuality = 65 })
    .Save("photos-watermarked.pdf");

Add File Attachments (PDF/A-3)

PdfEditor.Create(doc =>
{
    doc.Page(page =>
    {
        page.Size(PageSizes.A4);
        page.Content().Text("Invoice with attached XML data");
    });
})
.AddAttachment(new DocumentAttachment
{
    FilePath = "invoice-data.xml",
    AttachmentName = "invoice.xml",
    MimeType = "application/xml",
    Description = "Machine-readable invoice data",
    Relationship = DocumentAttachmentRelationship.Alternative
})
.Save("invoice-with-attachment.pdf");