Learn Mandarin on LuvLingua

LuvLingua is a language learning app that uses an interface that is more geared towards a younger audience. It's focused on vocabulary learning and listening skills. The basic app is free but the more advanced ones are paid.
Price: Free
Devices: Android, iPad, iPhone, and Web

Learn Mandarin on Fluenz

Fluenz is a language learning app that uses a video-based approach to teach users. Fluenz helps users build fluency (not pun intended) through various exercises which encourage retention of new vocabulary and grammar points.
Price: $408/month
Devices: Android, and iPhone

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