How to Find iPhone UDID for Beta Testing Registration

If you've ever been invited to beta test an iOS app legally without TestFlight, the developer probably asked for your UDID.

This mysterious string of characters is the key to Ad Hoc distribution. This guide will show you exactly how to find it on any iPhone or iPad in 2026.

What is a UDID?

UDID stands for Unique Device Identifier. It's a permanent, unique serial code hardwired into every Apple device.

• Old Format (iPhone 8 and earlier): 40-character hex string (e.g., 2b6f0...)
• New Format (iPhone XS and later): 25-character string with a hyphen (e.g., 00008030-001...)

Method 1: The Easiest Way (No Computer)

You don't need a cable or computer. You can use a secure web tool that installs a temporary profile to read the UDID.

1. Navigate to a trusted UDID finder tool (like BetaDrop's tool).
2. Tap "Get UDID".
3. Allow the download of the configuration profile.
4. Go to iOS Settings -> Profile Downloaded.
5. Tap Install. (This profile is temporary and only reads device info).
6. You will be redirected back to the website with your UDID displayed.

Method 2: Using Finder (macOS Catalina and later)

If you have a Mac, this is the official method.

1. Connect your iPhone to your Mac using a USB cable.
2. Open Finder.
3. Select your device from the sidebar.
4. Click on the text under your device's name (where it says "iPhone 15 Pro" or the storage capacity).
5. The text will cycle through information. Click until you see UDID.
6. Right-click (or Control-click) the UDID and select Copy UDID.

Method 3: Using Windows

On Windows, you can still use iTunes or third-party tools.

1. Open iTunes (if installed) or "Apple Devices" app.
2. Connect your iPhone via USB.
3. Click the secure Phone icon.
4. Click on the Serial Number field. It will toggle to show the UDID.
5. Right-click to copy.

Why do developers need this?

Apple's security model (walled garden) requires that every single device running a beta app (outside TestFlight) must be explicitly "allow-listed" by the developer. This is done by adding your unique UDID to the app's internal "provisioning profile".

Without your UDID, the developer literally cannot permit your specific phone to run their app.

Summary

Finding your UDID is a simple 2-minute process. Once you share it with a developer, they can send you custom builds of their apps that you can install instantly!