We are continuously improving our products and we have recently added many new features in Saaspose.Slides API. Our support team is working hard to cover all the features in the SDKs and documentation and updated SDKs will be available soon. Please have a look at http://saaspose.com/docs/display/slides/presentation+Resource for all formats supported by Saaspose.Slides.
Please also share which platform are you using, to help us share more detailed examples on PowerPoint to HTML conversion. In case of HTML conversion, Saaspose service returns the output as a ZIP file because there can be several support files with the HTML pages.
Support Developer, Saaspose Sialkot Team