I've been using Anki as called it by a sibling. I'm not super excited about it because everything about it is just a mess. But the are great pre-made decks and

I've been using Anki as called it by a sibling. I'm not super excited about it because everything about it is just a mess. But the are great pre-made decks and it's easy to find help because so many people use it. There is also memrise which seems to be gaining in popularity. If you are using Genki the publisher provides their own mobile apps.