Golden Shield Project (Great Firewall of Chine) ban tester

The Golden Shield Project (a.k.a. Great Firewall of China) is owned by the Government of China (MPS) and started in 1998. The system blocks content by preventing IP addresses from being routed through and consists of standard firewall and proxy servers at the Internet gateways of China’s ISPs. The banning of websites is mostly uncoordinated and ad-hoc, with some web sites being blocked and similar web sites being allowed or blocked in one city and allowed in another.

More infos from Wikipedia: Internet censorship in the People’s Republic of China

If you want to test if a website is visible from China, use this tool.