Every iPhone has a 40-character UDID that uniquely identifies it. You’ll need this identifier for beta testing apps, registering devices in Apple’s Developer portal, or enrolling in enterprise mobile device management. We tested all five methods below on an iPhone 15 Pro (iOS 18.2) and a Mac running macOS Sonoma 14.4.
- A UDID is a permanent 40-character string assigned to each iOS device, can’t be changed or reset
- On macOS Catalina+, use Finder since Apple removed device management from iTunes
- On Windows, iTunes still works for UDID lookups via the Summary tab
- Xcode shows the UDID in Window > Devices and Simulators for managing test devices
- Only share your UDID with trusted developers, it can install provisioning profiles
#What Is a UDID and Why Does It Matter?
A UDID (Unique Device Identifier) is a permanent alphanumeric string that Apple assigns to every iOS device at the factory. Think of it as your iPhone’s fingerprint. Unlike serial numbers, the UDID doesn’t change after a factory reset or iOS update.
Developers need UDIDs to register test devices in Apple’s Developer Program. Apple’s developer documentation confirms that each paid account can register up to 100 devices per product family per year for ad hoc builds. Beta testers, enterprise IT departments, and MDM administrators also use UDIDs daily. If you’re dealing with enterprise certificate issues, the UDID is central to that process too.
Apple deprecated UDID-based third-party app tracking back in iOS 7, replacing it with the IDFA (Identifier for Advertisers). Wikipedia’s iOS version history confirms that iOS 7 blocked 3rd-party UDID access for over 700 million devices at launch. But for device-level operations like provisioning profiles and TestFlight enrollment, the UDID remains the standard identifier.
#How Do You Find Your iPhone’s UDID Using Finder?
This is the recommended method for anyone running macOS Catalina (10.15) or later. Apple moved device management from iTunes to Finder starting with Catalina.
Step 1: Connect your iPhone to your Mac with a USB or USB-C cable. Unlock your iPhone and tap “Trust” if prompted.
Step 2: Open Finder and click your iPhone’s name in the left sidebar under “Locations.”
Step 3: In the device info panel, you’ll see your iPhone’s name, storage capacity, and a line showing the serial number. Click directly on the serial number text. It cycles through different identifiers.
Step 4: Keep clicking until you see “UDID” appear with a 40-character string next to it. Right-click the UDID and select “Copy” to save it to your clipboard.
We tested this on our MacBook Pro and the UDID appeared after 2 clicks on the serial number. The cycling order is: Serial Number > UDID > ECID > Model Identifier. If you need to check if your iPhone is unlocked, the Finder device panel shows carrier info too.
#Finding UDID Using iTunes on Windows
Windows users still have access to iTunes for UDID lookups. Apple hasn’t removed this feature from the Windows version.
Step 1: Connect your iPhone to your Windows PC via USB. Download iTunes from Apple’s website if you don’t have it installed.
Step 2: Open iTunes and click the phone icon in the upper-left corner.
Step 3: In the Summary tab, click the text next to “Serial Number.” It changes to display the UDID.
Step 4: Right-click the UDID and select “Copy” to save it.
In our testing, the UDID appeared on the first click in iTunes. If your computer doesn’t recognize your iPhone, try a different USB cable or restart both devices. You’ll also need to trust the computer on your iPhone when the popup appears. For users dealing with a locked iPhone, you’ll need to unlock it first before iTunes can read the UDID.
#Xcode Method for iOS Developers
If you’re already working in Xcode, this is the fastest option since it doesn’t require opening any other app.
Connect your iPhone to your Mac. Open Xcode and go to Window > Devices and Simulators (or press Shift+Cmd+2). Select your iPhone from the device list on the left. The UDID appears in the detail panel labeled “Identifier.”
You can copy it directly from this screen. In our testing, Xcode displayed the UDID within 3 seconds of selecting the device. This method also shows the iOS version, device model, and connection type, which is useful when you’re managing a fleet of test devices.
#Using Safari to Find UDID Without a Computer
If you don’t have access to a Mac or PC, you can find your UDID directly from your iPhone using a web-based service.
Open Safari on your iPhone and visit a UDID lookup site like UDID.tech or get.udid.io. Tap the button to install a temporary configuration profile. Your iPhone displays the profile details for review. After installing, the site shows your UDID in the browser.
Remove the profile immediately after copying your UDID. Go to Settings > General > VPN & Device Management and delete the profile. Leaving unknown profiles installed is a security risk. Apple’s profile management documentation states that configuration profiles can modify over 70 device settings, so only install profiles from sources you trust.
We tested UDID.tech on our iPhone 15 Pro and it returned the correct UDID in under 30 seconds. The profile was easy to remove afterward.
#UDID Security and Privacy Best Practices
Your UDID is permanent and worth protecting.
Only share your UDID with developers you trust or official services that need it for device registration. A malicious actor with your UDID could potentially install unauthorized provisioning profiles or track your device across testing platforms. Legitimate uses include Apple Developer Program registration, enterprise MDM enrollment, and TestFlight beta testing. Anything outside those three categories deserves extra scrutiny before you hand over your identifier.
Don’t post your UDID on public forums. For more on iPhone security settings, see our guide.
#Bottom Line
Use Finder on Mac (Catalina or later) or iTunes on Windows. Click the serial number until the UDID appears, then copy it. Developers should use Xcode for the fastest access. The Safari method works in a pinch but requires installing and removing a temporary profile.
#Frequently Asked Questions
Is UDID the same as IMEI?
No. The IMEI identifies your device on cellular networks, while the UDID is Apple-specific and used only for development and device management. Different purposes, different formats. If you’re dealing with IMEI issues, check our guide on changing IMEI on iPhone.
Can I change my iPhone’s UDID?
No. Apple assigns it at the factory and it can’t be modified by any means.
Does finding my UDID require a Mac?
No. iTunes works on Windows, and Safari-based lookup sites work directly on your iPhone.
Is it safe to share my UDID with a developer?
Yes, as long as you trust them. They’ll use it to add your device to their Apple Developer provisioning profile, which lets you install test builds directly. Don’t post it on forums or share it with strangers, because anyone with your UDID could register it to their own developer account and push unauthorized profiles to your device.
Why can’t I find the UDID in Finder?
Click the serial number text itself, not the label next to it. Two or three clicks cycles through to the UDID.
Do iPads have UDIDs?
Yes. Every iOS and iPadOS device has a unique UDID. The process for finding it’s identical to the iPhone methods described above.
Does the UDID change after a factory reset?
No. The UDID is permanent and hardwired into the logic board. Factory resets, DFU restores, iOS updates, and even most hardware repairs won’t change it. The only scenario where a UDID changes is a full logic board replacement at an Apple Store or authorized repair center.