Kanji study is a super powerful Android app to help you — you guessed it — study kanji. Frequently updated and expanded by developer Chase Colburn, Japanese Kanji Study is an app that exudes thoughtful design and allows for really thorough study. When you load up the app, you're asked to select which kanji sequence you'd like to use. This changes how the kanji are grouped in the app, and the options range from Japanese School Grades, JLPT levels, Frequency in media, and more, including to sort them however you see fit. From there, you're off to the races, and how you study is really up to you. There are flashcards, quizzes to practice everything from writing to meaning, and a full dictionary. Looking up a word includes reading examples for both the onyomi and kunyomi readings, common compounds that use that kanji, and more. One super cool add on is the dictionary from Outlier Linguistics, which adds some of the ancient forms of kanji, and really helps deepen your understanding.
Additionally, Chase has continuously expanded the app, and frequently adds new updates that dramatically improves the app. For example, just recently he added graded reading sets from the Kanji Learner's Course for an additional fee.
Really, Japanese Kanji Study is a supremely thorough app, whether you simply want a meticulously detailed dictionary, or you want to learn to write all the Jouyou kanji. If anything, it's a little too detailed, and easy to get bogged down if you're not quite sure what you want to practice. It's all very self-led, which is both a plus and a minus, as it's up to you to decide when you've learned a kanji and are ready to move on. Chase has said he's working on adding an SRS system to the app which I think would make things a lot easier, but it's yet to arrive. Finally, the add ons are really fascinating, but definitely expensive. Thankfully, there's a trial for most things so you can look before you leap. If you've got an Android device, you can't go wrong with Japanese Kanji Study.