I am interested in adding annotations support to my application. Specifically PDF (Adobe) anntoations.

I need a PDF library (preferably C# .NET Core) to read an input file (any format), generate some annotations, then export them to a PDF with adobe-capable PDFs.

So the functionalities required are:

  • Load input file (Pdf / word/ tiff)
  • Add annotations to it that are compatible with PDF standards
  • Export to PDF
  • Works with a .NET Core Docker container

Some of the annotation types I'm interested in are:

  • Redaction
  • Text box
  • Arrows
  • Are you looking for FOSS? Or are you open to paid commercial options? Are all your input files from the same source? Or do you need to handle random files from users/public?
    – Ryan
    Commented Mar 5, 2021 at 23:24

4 Answers 4


IronPdf is the C# PDF library you need. Support .Net5, Core 2/3x, Standard2.0, Framework4.0+ in Windows, Linux, MacOS, Azure and Docker. Nuget download: IronPdf.EAP

TIF, PNG, BMP, etc. all supported. Word files can be rendered by converting to HTML first.

See the simple example for annotations below. Redaction is coming soon.

// Create a PDF annotation object
var Annotation = new IronPdf.PdfDocument.TextAnnotation()

Title = "This is the major title",
Subject = "This is a subtitle",
Contents = "This is the long 'sticky note' comment content...",
Icon = PdfDocument.TextAnnotation.AnnotationIcon.Help,
Opacity = 0.9,
Printable = false,
Hidden = false,
OpenByDefault = true,
ReadOnly = false,
Rotateable = true

// Add the annotation "sticky note" to a specific page and location within any new or existing PDF.
Pdf.AddTextAnnotation(Annotation, 1, 150, 250);

Usual disclaimer: I work for Iron Software.


The PDF4NET library supports the features you asked about, except loading Word files.
The current set of samples is available here: https://github.com/o2solutions/pdf4net. The Annotations sample shows various annotations while the Redaction sample shows the redaction capabilities.

Disclaimer: I work for the company that develops PDF4NET.


The LEADTOOLS libraries supports many different types of annotations, such as the ones you mentioned, and even supports embedding them within a PDF document. The library also supports many document based formats such as PDF and Word, as well as just about any raster based images including tif. This is supported on .NET Core and Docker. Just as a disclaimer, I work for LEAD Technologies who develops this product.

Below is a snippet for how to embed annotations into a PDF document from a Word document using the DocumentConverter:

Using (DocumentConverter converter = new DocumentConverter()){
    converter.SetDocumentWriterInstance(new DocumentWriter());
    converter.SetAnnRenderingEngineInstance(new AnnRenderingEngine());
    DocumentConverterJobData jobData = new DocumentConverterJobData(){
        InputDocumentFileName = @"C:\temp\InputDocument.docx",
        InputAnnotations = @"C:\temp\InputAnnotations.xml",
        OutputDocumentFileName = @"C:\temp\OutputDocument.pdf",
        DocumentFormat = DocumentFormat.Pdf,
        AnnotationsMode = DocumentConverterAnnotationsMode.Embed
    DocumentConverterJob job = converter.Jobs.CreateJob(jobData);

You can refer Syncfusion PDF library.Essential PDF provides support for interactive annotations.You can add, delete and modify the annotation from the PDF documents.

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