
Babbel
I've used Babbel before, but almost exclusively the desktop app version. As I'm learning Spanish now, it was time to try the App version.
Babbel is one of the few apps that teaches grammar alongside the other elements of a language and teaches it well. It's broken into little chunks that are brought up when needed, just as the lessons are broken into chunks that make it feel like you can squeeze a lesson in here and there without it becoming a huge commitment.
The app has a variety of exercises that you can carry out, from typing in words, selecting the correct one, to following along and filling in the blanks in conversations. The latter doesn't hold back from presenting words and sentences that you haven't seen before but that you can guess from the context, which is a great method...