Not so-popular (however effective) study apps for the iPad/iPhone

1) Fatty Cat! - StudyCompanion - has a minimalist design, is extremely easy to use, and you won't feel bored while studying, because you will have a virtual cat companion.

The premium version costs $1.99.

2) Study timer: Keep going - has a very minimalist design, is easy to use, and is totally free. The app helps you count your study hours.

3) Encore - Personal Growth - The app has its own 3 kinds of study plans (mini, half, and full). You can choose any option according to your study plan. The app is totally free and, again, extremely easy to use with a simple structure.