Here's a collection of my fav language learning apps. I think these are all fun and functional. Easy to use, designed well, and each uses its own instructional method. I find that I absorb things from each because of the different teaching styles. Here's why I like them plus some screenshots of what the user experience is like. I am always learning a handful of languages, but I will showcase Korean for these apps.
LingQ teaches from reading content. You can read stories, articles, books, news, or you can import Netflix, Youtube, movies or music. Any content becomes an interactive lesson. You learn by saving words which become LingQs. Because you are learning in context, it's an easy way to learn vocabulary and increase comprehension.
Pimsleur teaches listening and speaking with audio lessons. It's a different approach, a more organic way of acquiring a language. You find that you anticipate responses and answers to questions by thinking in your target language. There are some quizzes and flashcards, but the audio lessons are the core of these courses.
Memrise teaches with audio clips of locals speaking their native language. It focuses on real life language and practical conversations. It has also fun games to strengthen vocabulary and grammar skills. Learning from locals is a great way to understand the spoken language and learn nuances of speech you can only get from native speakers.
Lingodeer is probably the most traditional language learning app. It is very structured, and teaches lessons in order and in great detail. Lingodeer is great if you are serious about understanding fundamental language concepts and complex grammatical rules, and especially if you like to learn with a structured learning experience.
Rosetta Stone teaches by dynamic immersive learning. It essentially throws you into your target language, and forces you to read and understand through pictures, with no native language guide. You learn by figuring it out as you go. Because you are 100% immersed in your target language, you can absorb content easily.