GroupDocs.Comparison for .NET is a flexible and feature rich library which allows you to compare documents for all popular document formats, such as PDF comparison, DOCX comparison, XLSX comparison and many more.

GroupDocs.Annotation for .NET is a comprehensive set of APIs that helps you build document annotation management applications in C#, ASP.NET and other related .NET technologies. You can create and work with all popular annotation types, such as area, point, text, ellipse, link, underline, polyline, arrow, distance, watermark, image etc for PDF, HTML, Microsoft Office Word, Excel spreadsheets, PowerPoint presentations, Visio, images, CAD drawing and various other formats. The document annotator library allows you to export documents after adding annotations, comments or highlighted notes back to its original format. It also gives you a handy set of data objects through which you can customize annotations as per your requirements.