Duolingo Yes, mobile app, No. I use Duolingo both mobile and on my PC. The app really helped me learn the languages duo to a very long travel time for work. I'm missing features from duolingo in the app though, for example the info card on lessons, which help greatly with understanding. But the most annoying part are the hearts they added. You have 5 in total. They recharge 1 heart per hour. So better don't make mistakes on mobile. PC Version doesn't use hearts.