Learn Estonian on Brainscape

Brainscape is a customizable flashcard language learning app where you can pick the language you want to learn and then create your own personalized learning path. It prides itself on being "the world's smartest flashcard app".
Price: $9.99/month
Devices: Android, and iPhone

Learn Estonian on 50 Languages

50 Languages is a mobile app that offers users a variety of features that make learning a language relatively easy. From pronunciation guides to verb conjugations, 50 Languages has a good set up to deepen your knowledge of your desired language. The app is free to download but you have to pay to remove ads.
Price: Free
Devices: Android, iPad, iPhone, and Web