Online Port Checker

What Does Our Port Checker Test?

Our online port checker tests whether a specific network port is reachable on a public IP address or domain. It can help you verify that a network service is accessible from the internet and troubleshoot connectivity or port-forwarding problems.

A port check typically involves three main elements:

• Destination: The public IP address or domain you want to test.
• Port: The numbered network endpoint associated with a service or application.
• Protocol: The transport protocol used for the test, such as TCP or UDP.

For example, if you have configured a server behind your router, you can test its public IP address and the port assigned to the service. The result can help you determine whether the service is externally reachable.
A port showing as open generally indicates that the tested connection or probe received a response from the destination. A closed result indicates that the destination did not accept the tested connection on that port.

How to Check If a Port is Open?

You can use our open port checker to test whether a port is reachable from the internet.

• Open the port checker.
• Enter the public IP address or domain name you want to test.
• Enter or select the port number you want to check.
• Click the Port Check button or press enter to initiate the port scanning.
• Review the result to determine whether the tested port is open or closed.

If you are testing a service hosted on your own network, use the public IP address assigned to your internet connection rather than the device’s private IP address.

Results You Get With Our Port Scanner

When a port scan is performed using our IP port scanner, you get very straightforward results that include:

• Port numbers that are scanned.
• Status of scanned ports: Open or Closed.

If you see “Open” next to a port name in the results, that the tested port is reachable and a service or network endpoint is responding to the connection or probe. While if you view “Closed” next to a port number, that the destination is reachable, but the tested port is not accepting the connection.

How Does Our Port Tester Work?

Our browser-based open port checker sends a network packets toward the selected port on the specified public IP address or domain. It evaluates the response to determine whether the tested port is reachable.

When you enter a domain name, the domain first needs to resolve to an IP address. The test can then target the resulting address and selected port.

The basic process is:

Domain/IP address → Destination port → Connection or probe → Network response → Port status

The result reflects whether the tested port is reachable from the location where the test is performed. It does not provide access to the destination or prove that the underlying system is secure.

Features of Our Open Port Checker

• Check individual ports: Test a specific network port and verify if port is open or closed without any technical steps.
• Test IP addresses and domains: Checks port status for a public IP address or supported domain name as the destination.
• Check port status: Determine whether a tested port is open or closed.
• TCP and UDP testing: Test supported transport protocols without installing desktop software.
• Common-port scanning: Scan predefined common ports with a single click.
• Browser-based: Run the port test directly from your web browser.
• Port-forwarding troubleshooting: Use external port testing to verify whether a forwarding rule is working.

How to Check Port Forwarding?

A port-forwarding test helps determine whether a port configured on your router is reachable from outside your local network.

Port forwarding normally follows this path:

Internet → Public IP → Router → Forwarded Port → Private IP → Local Service

The Port forwarding test can help verify that your forwarding rule is working and that the server application is accessible through your public IP address. You can do that using our port forward checker.

• Enter your public IP address or domain name.
• Enter the specific port number you’ve forwarded.
• Run the test (click on the “Check” button).

If the port is reported as “open” your forwarding rule is active and reachable from the internet. If it shows “closed” check your port-forwarding rule or firewall settings. Your router, firewall, or ISP might be blocking it. Or there might be no service currently listening on that port.

What Are Ports in Networking?

Ports are virtual endpoints that are used by network services and applications to communicate (send and receive data) over a network. They are identified by port numbers and work with transport protocols such as TCP and UDP to help a device direct network traffic to the appropriate service or application.

Internet devices communicate over networks via open ports. An open port is one that is accepting traffic, while a closed one is not. Ports are responsible for running services smoothly.

Why Check Open Ports?

According to a white paper by the SANS Institute, port scanning is the technique that many cybercriminals use to penetrate a network. Any vulnerability in these ports can expose the network to threats.

That is why you should check for open ports. When you check port status, you get help to:

• Troubleshoot connectivity issues.
• Prevent unauthorized access to the network.
• Test port forwarding rules on your router.
• Ensure services/applications are live and reachable.
• Check whether a firewall is preventing incoming connections.
• Review which services are externally reachable on a public IP.
• To confirm that a service is listening on the expected port.

Frequently Asked Questions

Is My Port Open?

Enter your public IP address or domain name and the port you want to test into our port checker. Run the port test to see whether the selected port is reported as open or closed.

Can this Port Tester Check UDP ports?

Yes, this open port check tool can scan UDP ports. Just enter the IP or domain name and select or enter the port you want to check. The port checker will check and show the status for that port.

What Is the Difference Between an Open and Closed Port?

Open port generally indicates that the tested service is reachable and accepting the relevant connection or probe. While, the closed port indicates that the destination is reachable, but no service or traffic is accepting the connection on that port.

Why Does My Port Show as Closed?

A port can appear closed because no service is listening, a firewall is blocking traffic, or port forwarding is incorrect. Also, the wrong IP address is being tested, the network uses CGNAT, or the ISP restricts incoming connections.

Can I Check a Domain Instead of an IP Address?

Yes, if domain testing is supported. The domain must resolve to the correct IP address for the test to reach the intended server.

Why Is My Port Open but My Application Not Working?

An open port only confirms network-level reachability of the tested port. The application can still have configuration, authentication, protocol, DNS, or service-level problems.