CHINESE LANGUAGE RESOURCES

Handian 漢典, a comprehensive Chinese online dictionary with both classical & literary and modern definitions, and extensive examples from primary sources:

https://www.zdic.net

汉字全息资源应用系统, a comprehensive Chinese online dictionary with both classical & literary and modern definitions, and extensive examples from primary sources:

https://qxk.bnu.edu.cn

Dictionary of Chinese Character Variants:

https://dict.variants.moe.edu.tw

(A Chinese character may be written with different variants, sometimes with significantly different appearances. Readers are especially likely to encounter character variants in manuscripts and old prints.)

歷史文字資料庫統合檢索系統，a database of how Chinese characters were historically spelled:

https://wcd-ihp.ascdc.sinica.edu.tw/union/search.php