Hi Wang, Currently our Mobile Associate API is not supported for web apps, I mean we do not have any public library for web apps. Though, if some one integrates our server side Product Advertising API in his web app, we would not prevent them to do that. I think that's the thing you mentioned like figuring out on your own. Some one can make a catalog of the digital products available in Amazon store and sell them out to the users of the app by using Product Advertising API. Thank you for posting.