Câu đối chữ Hán is an Android application developed by Nahu Studio. It is a free app that falls under the category of Education & Reference. The app offers a comprehensive collection of 300 Han Chinese couplets that are arranged in increasing order of difficulty. The app provides different forms of the couplets, including Han characters, Han-Vietnamese phonetic symbols, and translations.

One of the most remarkable features of the app is its ability to search for the couplets using Han characters or phonetic symbols. The app also comes with a Han-Vietnamese dictionary that can be used to search for the meaning of the Han characters used in the couplets. The app is ideal for those who are studying Japanese, Chinese, or Hán Nôm and want to improve their skills in reading and writing Han characters.