PDF Manipulation

Working Examples

PdfEngineOperations | WatermarkAndRotate | EncryptPdf | PdfMerge | PdfConvert

Standalone operations on existing PDF files using Gotenberg's PDF engine routes.

Standalone PDF Operations

Use PdfEngineBuilders factory methods to create typed builders for each operation.

Flatten

Merge form fields into static content:

using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Flatten()
        .WithPdfs(a => a.AddItem("form.pdf", pdfBytes)));

Rotate

Rotate pages by 90, 180, or 270 degrees:

// Rotate all pages
using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Rotate(90)
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

// Rotate specific pages
using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Rotate(180, "1-3")
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

Split

Split PDFs into chunks or extract page ranges:

// Split every 2 pages (returns ZIP)
using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Split(SplitMode.Intervals, "2")
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

// Extract pages and unify into one PDF
using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Split(SplitMode.Pages, "1-3,5", unify: true)
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

Encrypt

Password-protect PDFs:

using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.Encrypt(userPassword, ownerPassword)
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

Write Metadata

using var result = await sharpClient.ExecutePdfEngineAsync(
    PdfEngineBuilders.WriteMetadata(new Dictionary<string, object>
    {
        { "Author", "John Doe" },
        { "Title", "My Document" }
    }).WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

Read Metadata

Returns JSON keyed by filename:

var json = await sharpClient.ReadPdfMetadataAsync(
    PdfEngineBuilders.ReadMetadata()
        .WithPdfs(a => a.AddItem("doc.pdf", pdfBytes)));

// json: { "doc.pdf": { "Author": "...", "Title": "...", ... } }

Cross-Cutting Options

These options are available on all request types (HTML, URL, Office, PDF conversion) via BuildRequestBase.

Watermark

Add a background overlay:

var builder = new HtmlRequestBuilder()
    .AddDocument(doc => doc.SetBody(html))
    .SetWatermarkOptions(w => w
        .SetTextWatermark("CONFIDENTIAL")       // text watermark on all pages
        // Or target specific pages:
        // .SetTextWatermark("DRAFT", "1-3")
    );

Stamp

Add a foreground overlay (same API as watermark):

builder.SetStampOptions(s => s.SetTextStamp("APPROVED", "1"));

Rotation

Rotate pages inline during conversion:

builder.SetRotationOptions(r => r
    .SetAngle(90)           // 90, 180, or 270
    .SetPages("2-3"));      // optional: specific pages

Split

Split output during conversion:

builder.SetSplitOptions(s => s.SplitByPages("1-3,5", unify: true));

PDF Format Conversion

Convert existing PDFs to PDF/A or apply transformations:

var builder = new PdfConversionBuilder()
    .WithPdfs(b => b.AddItem("document.pdf", File.ReadAllBytes(pdfPath)))
    .SetPdfOutputOptions(o => o
        .SetPdfFormat(PdfFormat.A2b)
        .SetPdfUa()
        .SetFlatten());

var result = await sharpClient.ConvertPdfDocumentsAsync(builder);

PDF Encryption (Inline)

Encrypt PDFs generated from any conversion route:

var builder = new HtmlRequestBuilder()
    .AddDocument(doc => doc.SetBody(html))
    .SetPdfOutputOptions(o => o
        .SetEncryption(userPassword: "reader", ownerPassword: "admin"));

Merge PDFs

var mergeBuilder = new MergeBuilder()
    .WithAssets(b => b.AddItems(pdfStreams.Select((s, i) =>
        KeyValuePair.Create($"{i}.pdf", s))));

var result = await sharpClient.MergePdfsAsync(mergeBuilder);