Learn Mandarin on Mosalingua

Mosalingua is a language learning system that prides itself in having 11 million learners. It works by using flashcards to teach you new words and phrases. The app also includes a pronunciation guide, grammar tips, and a dictionary.
Price: Free
Devices:

Learn Mandarin on Rosetta Stone

Rosetta Stone is a language-learning app that started in the 90s for auditory learners.
Price: Free
Devices: Android, Apple Watch, iPad, iPhone, and Web

Learn Mandarin on Awabe

Awabe is a flashcard language learning app on Android. It focuses on vocabulary, offering as much as 4,000 words for each language.
Price: Free
Devices: Android, iPad, and iPhone

Learn Mandarin on LingQ

LingQ is a language learning app that uses the same logic for learning a new language as learning your native tongue: using content you already like. They have books, news, podcasts, sports coverage, politics, culture, and food to name a few.
Price: Free
Devices: Android, iPad, iPhone, and Web