UDID stands for Unique Device Identifier. It is a sequence of 40 letters and numbers that is specific to your device.
If you are a customer...
You need to provide this information to your developer in order to test a beta version of your app.
If you are a developer...
You need to register the UDID of your customer's device with Apple in order for the beta app to be ready for testing.
Nothing! We do not store any information related to your device. This information is obtained from your device by using a temporary profile and then, it is presented to you.
Once you close your browser window, the information is gone. If you need this information again, you will have to use the web tool once again.