HTML5 Offline storage can be used without an app. Part of the issue is not the storage, but how to run the app in the background to pre-fetch the content. Here's a table showing the limited access that hosted apps have. Looks like they do have access to certain device storage APIs, as well as desktop notifications, microphone, etc. https://developer.mozilla.org/en-US/Apps/Build/App_permissio... Here's another page comparing "packaged" to "hosted" apps which seems to imply they are mutually exclusive - https://developer.mozilla.org/en-US/Marketplace/Options/Pack...