What is a UDID?
UDID stands for Unique Device Identifier. For iPhone and iPad owners, it usually matters when a developer or device workflow needs to identify one exact Apple device.
What a UDID identifies
A UDID identifies a specific Apple device. Developers may use it to register devices for ad hoc builds, test distributions, or workflows where a device must be allowed before an app can run outside the public App Store.
What a UDID is not
A UDID is not your Apple ID, phone number, passcode, or iCloud account. It is also not the same thing as your device serial number or IMEI, even though those identifiers may appear near each other in technical workflows.
Should you keep it private?
Treat your UDID as device-identifying technical information. It is not enough to unlock your device or access your Apple account, but it can identify your device in systems that store or compare UDIDs.
Need the identifier?
Get your UDID in Safari
Open this page on the iPhone or iPad you want to identify and use the profile flow to copy the result.
Common questions
Why does a developer need my UDID?
A developer may need it to register your device for ad hoc testing or a private app build.
Can my UDID change?
For practical app testing workflows, you should treat the UDID as a stable identifier for that physical device.