Anki allows you to add cards through the Ankiweb interface, in addition to having a more flexible card/note data model than most of the alternatives. The iOS A

Anki allows you to add cards through the Ankiweb interface, in addition to having a more flexible card/note data model than most of the alternatives. The iOS Anki interface is pretty expensive at $25, but you can do everything through the web if you want, albeit clumsily.