PDF Viewer is available for the two most common mobile platforms: iOS and Android.
We're always watching the market and exploring where to go next. Our current focus is Web - we already shipped PSPDFKit for Web and are exploring ideas how we can create value with a business product as well.
We're already working on bringing PSPDFKit to both Windows and macOS, which is a first step towards bringing PDF Viewer to these platforms. No promises though - we are still very much focussed on our two existing PDF Viewer apps and have big plans.