Each iOS device has a Unique Device Identifier (UDID) which is a long serial number. When we want to show you a demo of an app (one that isn’t in the App Store), we need the UDID for each device that you want to view the demo on.
Find your UDID using iTunes
1. Launch iTunes on your computer and connect your iOS device.
2. Select your device so that you can it’s Summary. In the latest version of iTunes, you select your device from a row if icons at the top of the screen and just below the play button.
3. Click on your device’s Serial Number to reveal it’s UDID.
4. Copy the UDID by choosing Edit > Copy (or Cmd + C).
5. Paste the UDID in to an email and send.
Find your UDID without using iTunes
Update: All of the apps we’ve tried (UDID Finder, UDID Sender etc) produce bogus UDID’s so we don’t recommend them.
Most reliable ways of finding your UDID without using iTunes, require you to install something or sign up for a service. Since we’re not keen on that approach,until we find a solution that we’re happy with, please the iTunes method above.