Dynamsoft PDF Annotation SDK for .NET

Add PDF Annotations in C# / VB.NET; Add-on to Dynamic .NET TWAIN

Annotate PDF in your .NET WinForms Application

The PDF Annotation add-on of Dynamic .NET TWAIN enables you to add PDF annotation functionality to your WinForms applications in C# or VB.NET. This allows for markup and objects to be superimposed directly onto a PDF document, without changing the underlying master PDF. Annotations include underlines or highlights, notes and comments, circles, rectangles, and more.

By integrating with the PDF Rasterizer add-on, you can open existing PDF documents, add annotations and then save PDF file as images.

Built-In Annotation Objects and Basic Features

  Text Rectangle Line Ellipse
0 - 100% Transparency
Customizable fill color
Customizable line color
Customizable font
Change layer
Rotate 90 degrees


  • Set the order of annotations by using "pull to front" and "push to back" .
  • Allow any object to be rendered at transparency levels from 0 - 100%.
  • Add any number of annotation objects to an image. These objects can be moved and resized independently.
  • Multiple annotations can be selected as a group so that they are moved as one object.
  • Annotations can be printed with the base image.
  • Text annotations can be rotated with the image in 90 degree increments.
  • A smooth dynamic display. Objects are shown with an outline when resizing, so the resulting size is clear.
  • Responds to numerous mouse clicks events, allowing custom scripts or actions to be implemented.
  • Annotations can use custom controls by making use of the Annotation Data class.
  • All icons for all annotation types are fully customizable at any size.
  • Intuitive and powerful interface.