Mondly is a mobile app very similar to Duolingo (which does not support Chinese).
- more or less straight course to take, no distractions
- It has several languages besides Chinese. The course is the same for all languages,
- Gamification aspects, like leaderboards, scores, points, strikes, etc.
- Nice UI
- varied lections, multiple choice with pics, reading, writing, speaking with voice recognition into the phone, "simulated" chat which you accomplish with voice recognition
- totally not very well suited for Chinese beginners, as there are no explanations of counting words, grammar, etc.
- inconsistencies in the learning, sometimes there are synonyms in one lection but will not be references later or repeated.
- not very coherent. Because there are numerous lection types (See pro), one sometimes stumble upon a word in one question (like reading), but not necessarily see that word again in writing or voice recognition. This in combination with the missing learning system is the app's major issue IMO
- there is no tracking of mistakes/words/spaced repetition what-so-ever. So it is very similar to a book that you take by yourself.
If you already have a little exposure to Chinese, it might be helpful to boost vocabulary size and fill out blanks. The app has a lot of voculary. If you don't use Pinyin, but Hanzi and listen carefully to the voices, it helps for listening and reading.