Using GroupDocs.Conversion for .NET, it is possible to convert any PDF document to HTML file in C#. Conversion process or feature is not limited to PDF files only. You can convert any supported file format to HTML.
GroupDocs.Conversion for .NET is a back-end API that can be integrated in any (new or existing) .NET application.
C# Example: How to Convert a PDF to HTML
This API can convert any source document to a markup format which in general is an HTML conformable format.
You can see that sample PDF has some visuals and text. And the resultant HTML covers everything.
You can download our GitHub open-source example project in order to evaluate the API. In case of any issue, you can raise it on forum.