This is the best overview of spaced repetition research I have seen online or offline. It's thorough, well-argued and probably covers more than you were looking for. It's not specifically about Chi... Read more.

gwern.net

This site (originally a book) explains the difference between commonly mixed up (traditional) characters, published by Taiwan's Ministry of Education. As it says in the introduction, the main purpo... Read more.

language.moe.gov.tw

HiNative is a Q&A site where you can ask people all over the world about culture, language, anything. We support over 100 languages. Read more.

hinative.com

Teachers give feedback in many different ways, some terribly bad, others very good. The bad ones let you struggle for hours just to correct your essay, not necessarily learning much on the way. The... Read more.

hackingchinese.com

This is a digital version of the official authoritative stroke order standard used in China. It is sorted by stroke and is not searchable, so it's a bit hard to use. Thus, other resources will ofte... Read more.

yuke.blcu.edu.cn