In this tutorial, we are going to cover how to implement Document Viewer in Asp.Net Core 3.0 application using visual studio 2019. There are many file viewer libraries for .NET Framework. But now in this tutorial, we will use GroupDocs.Viewer to preview files in different formats like pdf, docs, excel, power point, outlook, visio, and many others in Asp.Net Core 3.0 application. And if you want to read more features about GroupDocc.Viewer, then you can read here.