GFW Check
Probe the same target from a mainland China node and an overseas node, then compare the results to detect blocking.
This tool compares probes of the same target from a mainland China node and from this site (overseas). Unreachable in China but reachable overseas usually means the target is blocked. The verdict is based on real network probes and is indicative only.
FAQ
The tool probes the same target from a mainland China node and from this site (overseas) at the same time, then compares reachability: unreachable in China but reachable overseas usually means the target is blocked.
Domain mode sends an HTTP(S) request to a full URL and is best for checking whether a website is blocked. IP mode sends ICMP pings to an IP to see whether it responds from China. IP + port mode opens a TCP connection to a port to see whether it is filtered.
The verdict is only an inference from network reachability. Unreachable in China but reachable overseas can also be caused by the target blocking Chinese IPs, or by a temporary issue on the China node, so we say "likely". Try again later or cross-check with another mode.
Many hosts and firewalls do not answer ICMP at all. If both China and overseas show 100% packet loss, it only means the target does not reply to ping, not that it is blocked. Use domain or IP + port mode instead.
The check never falls back between protocols. Only an explicit scheme lets us tell whether that protocol (especially HTTPS/TLS/SNI) is blocked versus the target being unreachable; omitting the scheme could misreport an HTTPS-only block as not blocked.
The China probe node limits requests per IP per day (50 requests per endpoint per 24 hours by default). Please try again after the limit resets.
No. Check inputs and results are not stored. The China probe node sees your request IP for rate limiting only.