Digital Annotation via C# .NET SDK

Universal Document & Image Annotator REST APIs to build C# .NET based tools. Render annotated output with export/import feature.

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GroupDocs.Annotation Cloud SDK for .NET

GroupDocs.Annotation Cloud SDK for .NET


GroupDocs.Annotation Cloud REST API for .NET allows you to programmatically work with business document annotation operations and develop tools using C# and other .NET technologies. The tools that you develop using our annotation SDK for .NET APIs, enable your end-users to annotate files of supported file formats, such as PDF, Microsoft Word, Excel, PowerPoint, Images and various other formats. Apply redactions, watermark overlays, sticky notes, pointers and text markups etc. The open-source SDK works as a wrapper for cross-platform .NET REST APIs. Apply annotations as drawings or text markups.

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Advanced Document Annotation REST API Features



Apply/remove annotations, drawings & text markups


Retrieve metadata information of document


Get annotation data for supported file formats


Import/export list of document annotations


Convert annotated document to PDF


Save annotated document & fetch its storage link


Annotate documents of multiple file formats


Text redaction application support for Microsoft PowerPoint


Perform annotation in header/footer section of Word Documents


Work with Document Annotations

GroupDocs.Annotation Cloud SDK for .NET allows you to utilize all the features of the GroupDocs.Annotation REST API which provides a number of ways to deal with the annotations. It not only allows retrieving annotations from documents but also adds (exports) annotation to a document and retrieves the resultant document as a stream. The below-mentioned example shows how easy is to import annotation using the SDK for .NET:

Import document annotations - C#

// Get your AppSID and AppKey at (free registration is required).
var configuration = new Configuration(AppSID, AppKey);
var apiInstance = new AnnotateApi(configuration);

// Set request.
var request = new GetImportRequest()
    filePath = "docs/document.docx"

var response = apiInstance.GetImport(request);

Robust Set of Annotation Tools

In GroupDocs.Annotation Cloud SDK for .NET, support for two primary annotation types is available. Each annotation type then further has numerous sub-types. The two primary types are; drawing based annotations and text-based annotations or markups.

Text-based annotations are used to add comments to text selections, hide confidential text by redaction, apply underlines or strikethroughs to mark text, and stick notes to rich text.

Whereas, graphical annotations are used to highlight area with rectanlgular shape and add notes to it, hide classified image or text, pick particular point within document and apply notes to it, drop arrow to an object to point towards it, draw lines and shapes, apply text-based watermarks, and distance based annotations.

Easy Integration

Integration of GroupDocs.Annotation Cloud SDK in to your C# or other .NET based applications is pretty easy and straight-forward. Simply create an account at GroupDocs.Cloud and get the App SID & App Key and you are good to go.

Easy Customization

Our Annotation SDK for .NET is open-source, and has an MIT license. GroupDocs.Annotation Cloud SDK is reliable, scalable and fully tested toolkit. So you can use it and even customize it as per your requirements free of charge.

Interactive API Explorer

Check our annotation API right now in your browser using Swagger based API explorer that lists all the features of GroupDocs.Annotation Cloud API for .NET. Provide your desired parameters to any feature and Try it out. You can visit our API Explorer now.

Support and Learning Resources


GroupDocs.Annotation Cloud Product Family also includes SDKs for other popular languages as listed below: