Obenkyo

In this easy to navigate menu, you can see aspects of learning Japanese listed in the center. Pressing on the left side of a selection leads to Study, while on the right side to Test.

Obenkyo has extensive vocabulary, with lists divided into several proficiency levels. You can edit the lists manually, selecting which words appear on tests, but the lists are still very long and a little painstaking to manage. The color of dots tells you whether you were getting the word right or wrong on tests.

Similarly for kanji, you have a large database divided into several proficiency levels. You can learn the meanings of the kanji and practice writing it.

You can test kanji in a variety of ways, including writing. The system seems just right - it's lenient enough to not make the hard art unbearable on a phone, but it will detect stroke order, number, and direction.

You can pull up a "More" pane to see your mistakes and the corrections. If you think Obenkyo is wrong, you can press "Recognition mistake" and send error reports.

You can test your knowledge of numbers in a few ways, one of which includes reading large numbers. It's an effective way to gain quick proficiency over the system.

Obenkyo also has useful particles tests, which leave blanks in full sentences for you to fill. It's a great tool for a more natural way to study the language, and this is often tested in classes. You can press on words with kanji to see furigana.

It's very useful to see your mistakes in the "More" tab, because you can also see a translation for your sentence.