Port Checker
Test whether a TCP port is open or closed on any IP address or hostname.
TCP Connection Test
This tool attempts a real TCP connection to the specified host and port. If a connection is established, the port is reported as open.
External Perspective
Checks are performed from our server, so the result reflects what the public internet can reach, bypassing your local network or VPN.
Firewall & Filtering
A closed result may mean the port is not listening, or that a firewall is blocking access. Firewalled ports may show as closed rather than filtered.
Frequently Asked Questions
Can I check a port directly from the URL?
Yes. You can use the format portcheck.ing/host:port to check a port instantly — for example, portcheck.ing/8.8.8.8:53 or portcheck.ing/example.com:443. The result will appear automatically without needing to fill in the form.
What does it mean when a port is "open"?
An open port means a service is actively listening and accepting TCP connections on that port. Our tool successfully established a connection to it.
What does "closed" mean?
A closed or filtered port means no service is listening there, or a firewall is blocking the connection attempt. The target host refused or did not respond to the connection.
Can I check UDP ports?
Currently, this tool only supports TCP port checks. UDP is connectionless and cannot be reliably tested the same way without protocol-specific probes.
Why does this differ from checking locally?
Checks run from our external server. A port visible to you locally may be blocked by your ISP, a cloud firewall, or a security group. This tool shows what the wider internet sees.
Which IP ranges are blocked?
Private IP ranges (192.168.x.x, 10.x.x.x, 172.16-31.x.x) and loopback addresses are not reachable from external servers, so they will always return closed.
Is there a rate limit?
To prevent abuse, excessive requests from a single source may be throttled. This tool is intended for legitimate network diagnostic use.