Few days ago I wrote about Duolingo, a fun app to learn new languages. The popular app features many languages, but incidentally Chinese is missing. If you’d want to learn Mandarin Chinese, fret not. Available for both Windows Phone and Windows 8 devices, HANYU.CO(hanyu.co) is a great app dedicated to the Chinese language. Brought to you by Spiffy Ventures, the company that developed Effectual, HANYU.CO is a complete Mandarin Chinese language learning service with hundreds of useful lessons, guided learning, progress reporting, and useful tools like a dictionary and HSK vocabulary lists.