As soon as you run the program you will see a list with all the WiFi networks close by, and they will appear in green or red, depending on whether or not their password has been identified. You can instantly view the password by clicking on any one that is green, and copy it to your clipboard.
Thus, you can know if the password that it displays (which the router has by default) would work to easily access your network.
You can choose for it to update automatically in the program settings, or even to vibrate each time there is an update to the WiFi network list.
pulWiFi is one of those apps that shouldn't be taken lightly, as while it is very easy to use and can help you solve problems with your own connection, the consequences of using it on unknown networks can be very strong.