Thanks for considering Aspose.Slides.
I regret to share that provision for exporting PPT/PPTX to HTML is unavailable in Aspose.Slides for .NET. One need to manually implement his parser to export presentation text to HTML. The only available option is to export slide as image and add slide as image in HTML page. Please follow this link to see how to generate slide thumbnails.
We are sorry for your inconvenience,