For iOS, you don't need a jailbreak to download it either! No, it is not a web app. It just uses some download protocol I don't know about. Of course, there are more emulators out for the jailbroken iOS devices.
If you want to get a ROM, go to the app and click the magnifying glass. Then click on the first result (ROM downloads for the app only work at doperom.com, but I think you can load other ones on using iTunes share thingy).