Learning a new language can be fun if not quite challenging, especially when the language uses a completely different writing script or grammar pattern then you're used to. Some people choose to learn for funsies while others do it for their jobs or whatnot. As an Asian Studies major, I am required to study any Asian language of my choice (and I chose Korean) and frequently use different language-learning apps to sharpen my skills. Here is a list of apps I've used and tested out over periods of time I believe are worth downloading.
1. Duolingo
I freaking love this app! The overall appearance is spot on but I also like how functional and easy it runs. Each language starts out with the Basics, Phrases, Basics 2, and so on. Duolingo brings out the fun part of learning with games to keep it entertaining. And if you're super talented and feel the basics are too easy for you, you can test out to the next level.
2. Quizlet
Not necessarily a language-learning app, but if you're in a foreign language class you can look up your class by the university to see if any classmates have made any vocabulary words for a particular lesson. It's super helpful for remembering vocabulary words for each lesson and they have fun learning games to keep it interesting.
3. Babbel
Such a great app to further help your language learning skills. Unfortunately, unlike Duolingo and Memrise, you do have to pay after a period. I loved Babbel mainly because it was more about the technical side of grammar. I would still recommend it even though you do have to pay because it is so worth it.
4. Memrise
I've only used Memrise for Korean but it has a lot of other foreign languages as well. In particular for Korean, I find the combo of Quizlet & Duolingo to satisfy me but if you're focusing on more European-type languages, Memrise could be for you.
5. Tandem
I recently downloaded the language-exchange app Tandem and guys, this is the best thing ever. The people I've met on there are the sweetest people ever, so shout out-out to the Spanish-speaking community for being patient with my very basic Spanish skills. You basically set a profile about yourself, the languages you want to learn, what do you want to get from using the app, etc. Then you go search for people with the same interests and language as you and start chatting! You can also do video chats as well as audio ones if you're too shy for face-to-face.