Duo lingo app
How to create the app?
If you have an Android, iPhone, iPad, or Windows phone, you just need to download it from the app store on your phone or iPad. It is a free application. Some people have put out fake versions and try to charge for it. Ignore those. The only thing that costs money is the Testing Center, which is a separate thing and no one is required to purchase it. :)
I'm so bad, I always forget there is a link for that one. Dunno what I'd do without you ;)