Network & DNS
Port Checker
Check one public TCP port with a direct connection. A timeout is not proof the port is closed. This is not a port scanner.
Results appear here.
What the result means
You name one public host and one TCP port from 1 to 65535. The Worker opens a single connection and waits up to five seconds for the handshake. Reachable means that handshake finished. A timeout, a reset, or a refusal means the check did not complete. None of those is proof the port is closed, because a firewall can drop the probe while the port stays open on another network. One request checks one port. The page does not walk a list, and it is not a scanner. Private, loopback, and link-local hosts are rejected before the socket opens. Use the website check when you need an HTTP status rather than a TCP handshake.
Related tools
Questions
Can I check port 22?
Yes, if you type 22 as the single port. The page tries that one TCP connection. It does not also try 80, 443, or any other number.
Why did 443 time out?
The edge did not finish a TCP handshake in five seconds. That can be a filter, a slow host, or a port that is not accepting connections from Cloudflare. A timeout is not proof the port is closed.
Is this a port scanner?
No. Each request names one host and one port. There is no list, and a result that did not complete is not reported as closed.