Our whole family uses DuoLingo and we love it. Particularly in the summer it helps our kiddo keep her learning brain active :) I've studied Italian, French, and Spanish on the app and love how they keep updating it and keep it fresh.
I LOVE Duo lingo. I'm revisiting my 4 years of Latin from high school and then switching between German and Spanish. It's a fun easy to use app that I have found myself not only enjoying but shocked I am so easily and fluidly switching between languages I've never spoken or learned before.