Check whether a TCP port is open and reachable on a public IP address or host.
How to use Open Port Checker
Enter a domain or public IP address, or click Use my IP to test your own connection.
Enter a port number or click one of the common ports.
Click Check port. Open means something accepted the connection; closed or timed out means it is blocked or nothing is listening.
Worked example
After forwarding port 25565 on your router for a Minecraft server, click Use my IP and the 25565 button. If it shows closed, check the router rule, the server’s firewall and that the server is running.
Why is my port closed even though I forwarded it?
Common causes are a firewall on the computer, the service not running, the wrong internal IP in the rule, or an ISP that uses carrier-grade NAT so you have no public IP.
Can I check private IP addresses?
No. The check runs from our server over the internet, so only public addresses can be tested.
Put this guide into practice
Open Port Checker — Check whether a TCP port is open and reachable on a public IP address or host.