Tools for Chinese traffic (PRC).
Anybody, who receive traffic from PRC (People's Republic of China, exclude
special administrative regions Hong Kong and Macau) you may check
your sites or sites where you send traffic using these tools:
1. http://www.blockedinchina.net/
2. https://en.greatfire.org/
(this tools also indicate "forbiden" keywords in search engines:
Baidu and Sina Weibo).