Yes, 워드스프링-영단어암기 is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
워드스프링-영단어암기 is free.
To get estimated revenue of 워드스프링-영단어암기 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.