Converting from PDF to HTML

Writing a program to do it is definitely not trivial. If you don't find any .NET Library to do this (I couldn't, at least not free), I would just download this and invoke it programmatically to get my html.

If you have the time to spare and/or PDFToHtml does not produce acceptable output for you, you could use iText to write the program yourself. It's a very mature free pdf library. I've used it in the past to manipulate PDFs (merge, create, etc).

UPDATE

As noted in the comment by Quandary, the PDFSharp library offers a more relaxed license (MIT) compared to the Commercial or AGPL license offered by iText. Keep this is mind when choosing your library. I have not used the PDFSharp library myself and I don't know how they compare in terms of functionality.

You can download this free tool: PDFToHTML

Then in your program just fork a new process and run the executable passing the PDF file. I just tested it now and it seems to work ok.