Language

Translate Chinese to English
Youdao
https://fanyi.youdao.com/index.html#/

Translate Classical Chinese to Modern Chinese
文言文翻译
https://app.gumble.pw/wenyan/

說文解字 online
with Duàn Yùcái “說文解字注”, 釋名 Shiming, 爾雅 Erya, 方言 Fangyan, 廣韻 Guangyun définitions and glosses
http://www.shuowenjiezi.com

Primary Sources

Chinese Text Project
Open-access digital library to pre-modern Chinese texts
https://ctext.org/