Test whether a public service answers on an allowed TCP port

For web teams checking a launch or tracing a fault, this test provides an immediate point of reference. Test whether a public service answers on an allowed TCP port.

Test whether a public service answers on an allowed TCP port. The result organizes the useful evidence so you can focus the diagnosis.

How to use

Enter the domain, IP address or URL of the public service and the TCP port you want to check in the field provided.
Launch the test so the request can be sent and the service response can be examined.
Read the result to see whether the service answers on the tested port.
Use that evidence to guide diagnosis, such as checking a firewall rule, a listening service or a network path.
Erase the field before testing another target or when you do not want the entry to stay visible.

Example

Suppose you are checking a public service before a launch. Enter its domain and port, run the test, then see whether the reply confirms that the service is reachable. The outcome gives you a starting point for deciding whether to investigate the service, the network or a filtering rule.

Limits and formats

This checks a TCP port only; it does not prove that a UDP service or another feature is working.
The target must be public and authorized for testing; do not scan systems without permission.
A firewall or filtering rule can block the reply even if the service runs locally.
A negative result is not a full diagnosis of the application or server configuration.

Where processing happens

The domain, IP address or URL you enter is sent to the YOORfree server, which performs the DNS lookup or connects to the target site itself and returns the result. No file is uploaded. The request is therefore made by the YOORfree server rather than directly from your browser to the target.

Frequently asked questions

What does an open port mean in this test?

It means the service replied on the requested TCP port at the time of the test. It does not prove that the application is healthy or that the port will remain reachable. Read the result together with firewall, service and network context.

Can I test a private address on my local network?

That case is not guaranteed here. Because the request is made by the YOORfree server, a private address that is not exposed to the internet will not be reachable. Use a public or authorized target, or test from your own network.

Does this replace monitoring software?

No. It gives a one-off check on one TCP port. For availability tracking, alerts or historical trends, you still need a dedicated monitoring setup.