Add text markup, shapes, watermarks, and comments to PDF documents.

Annotate PDF Documents with C#

Add and manage annotations in PDF files programmatically — no Adobe Acrobat required.

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How to Annotate a PDF in C#

GroupDocs.Annotation for .NET makes it easy to annotate PDF documents:

Open the PDF with an Annotator instance.
Create and configure the annotation you need.
Add the annotation to the document.
Save the annotated PDF.

Sample annotations Copy

// Annotate a PDF document

// Open the PDF with an Annotator instance
using (Annotator annotator = new Annotator("input.pdf"))
{
    // Create an area annotation
    AreaAnnotation area = new AreaAnnotation
    {
        Box = new Rectangle(100, 100, 200, 80),
        BackgroundColor = 65535,
        PageNumber = 0,
        Message = "Important"
    };

    // Add the annotation
    annotator.Add(area);

    // Save the annotated PDF
    annotator.Save("annotated.pdf");
}

dotnet add package GroupDocs.Annotation

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Full Control Over PDF Annotations

Add every annotation type to PDF documents and manage them with a simple API.

Text Markup

Highlight, underline, strike out, or replace text in PDF files.

Shapes & Watermarks

Draw shapes and stamp watermarks or images onto PDF pages.

Manage Annotations

Get, remove, import, and export PDF annotations.

Read PDF Annotations

Retrieve the annotations stored in an annotated PDF document:

C#

Download result Copy

//  Open the annotated PDF
using (Annotator annotator = new Annotator("annotated.pdf"))
{
    // Get all annotations
    List<AnnotationBase> annotations = annotator.Get();

    // Inspect each annotation
    foreach (AnnotationBase annotation in annotations)
    {
        System.Console.WriteLine(annotation.Message);
    }

    // Save the document
    annotator.Save("output.pdf");
}

dotnet add package GroupDocs.Annotation

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Annotate PDF Files

GroupDocs.Annotation for .NET lets you add, edit, and remove annotations in PDF documents. Highlight or strike out text, draw area and shape annotations, stamp watermarks and images, and attach threaded comments — then save the result back to PDF.

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