Gridded is a powerful, free flashcard system
specifically designed for learning languages. The app has a uniquely visual spaced repetition system that allows you to
see at a glance, based on the hues of your flashcards, which cards need reviewing and how long before each card next
needs to be reviewed.
The app includes editing tools for consolidating groups of flashcards from multiple sources and dealing with differences and discrepancies between those sources; the ability to pronounce the words on your cards as you study them with customizable text-to-speech voices; and the ability to sync your data between an unlimited number of Mac and iOS devices.
These features are explained in detail in a series of free video tutorials that come with the app. The app also comes with built-in flashcards for learning the capitals of Mexican states, the atomic weights of the periodic table, and both Japanese syllabaries.
This is a full version. There are no ads and the in-app purchases are simply an unobtrusive pay-what-you-want system in case you would like to pay for the app.