To try application :
1.Click on download button on the right side and download application.
2.Double click on downloaded zip archive(no installation required)
3.Type name of the computer to check and port which would you like to check
4.Click on test
If application returned "Port Available" then this port is open on computer you have specified.
Full versions has no limitations and include sources (in Visual Studio 2008 and Visual Studio 2010).
To buy full version click on "Full version tab".