Unique device identifier, or UUID (Universally Unique Identifier), plays a key role in the Android ecosystem. It's your device's digital fingerprint, used by app developers to track installs, ad networks for targeting, and system services to sync data. Users often need to recognize this code when debugging applications, setting up server access, or solving software licensing problems.
In modern versions of Google's operating system, access to persistent identifiers has been significantly limited for privacy purposes. If previously getting Android ID or a serial number was a matter of a couple of seconds, now the system requires special permissions or the use of debugging tools. However, there are several proven methods that allow you to extract the necessary information about your device without losing the warranty or compromising the integrity of the system.
In this article we will analyze in detail the technical and software methods for obtaining identifiers. We will look at both standard settings available to every smartphone owner, and advanced methods using console utilities. You will learn the difference between different types of identifiers and what specific code is required in your particular case.
What is a UUID and why do you need it on Android
The term UUID in the context of mobile devices can be interpreted differently depending on the access level and the specific task. Globally, this is a 128-bit number that guarantees uniqueness in space and time. For an ordinary user, this is a set of characters that distinguishes it from millions of other devices of the same model. Developers use this identifier to link licenses, prevent fraud and analyze the user base. If an application crashes or requires reactivation, often the reason lies precisely in a change or incorrect reading of this code by the system. Understanding the nature of the identifier helps to avoid many software compatibility problems. Samsung Galaxy or Xiaomi Redmi from millions of other devices of the same model.
Developers use this identifier to link licenses, prevent fraud, and analyze the user base. If an application crashes or requires reactivation, often the reason lies precisely in a change or incorrect reading of this code by the system. Understanding the nature of the identifier helps avoid many software compatibility problems.
⚠️ Attention: Do not share the full device identifier with unknown sources. Attackers can use it to clone a digital profile or target attacks on your account.
It is important to distinguish between several types of identifiers, which are often confused. Android ID generated during the first boot of the system and can be reset during a Factory Reset. Serial Number is a physical number programmed by the manufacturer. Advertising ID (GAID) was created specifically for marketers and can be reset by the user in the settings. Each of them performs its own function, and substituting one for the other can lead to errors in the operation of services.
If you are a developer, use Advertising ID for analytics so as not to violate the Google Play privacy policy. Android ID is better suited for internal debugging.
Viewing the ID through the settings menu
The safest and most accessible way to find out basic information about the device is the standard settings menu. Smartphone manufacturers implement this section in different ways, but the general logic remains the same. You do not need to connect to a computer or install third-party software.
Usually the path looks like this: go to Settings → About phone → General information or Settings → System → About device. In some shells, for example MIUI or OneUI, you need to click on “All characteristics” or tap on the version several times firmware to open the extended menu.
- 📱 Look for the “Serial Number” item - this is the closest analogue of a permanent UUID for a physical device.
- 🔒 The “Status” section often contains the IMEI and device code, which is used by operator networks.
- ⚙️ The Android ID may be displayed in the “For Developers” menu if this option is not hidden by the manufacturer.
It is worth noting that in pure Android 10 and later, access to immutable identifiers is closed for third-party applications. Therefore, in the settings menu you will only see data that the system considers safe to display. If you need a software UUID for debugging, this method may not be enough.
Using ADB to get accurate data
For professionals and advanced users, the most reliable tool remains Android Debug Bridge (ADB). This utility allows you to send commands directly to the device shell, gaining access to system variables that are hidden from the normal interface. The method requires a computer with installed drivers and platform tools.
Before starting work, you must activate the debugging mode. Go to Settings → About phone and quickly click 7 times on the “Build number” item. After the message “You have become a developer” appears, go to the new menu and turn on the switch USB debugging. Connect your smartphone to the PC with a cable.
adb shell settings get secure android_idThis command will display the value Android ID, which is often used as a unique session key. However, if you need a hardware serial number, the command will be different. Enter the following query into the terminal:
adb shell getprop ro.serialnoThe result of the command will display the factory serial number of the device. Please note that on some emulators or custom firmware this field may be filled with the value "unknown" or a dummy character set. In such cases, access to the file system with superuser rights is required.
☑️ Preparing to work with ADB
Specialized applications for diagnostics
If using the command line seems too complicated for you, applications from the store will come to the rescue. Google Play. There are many diagnostic utilities that collect all available information about hardware and software into a convenient interface. They automatically read system properties and display them in a readable form.
Popular solutions such as Device Info HW or AIDA64provide detailed reports. In the “System” or “Device” section you will find fields Android ID, Serial and other technical parameters. These applications work without root access, using public APIs of the system.
| Application | Access type | Shows Android ID | Shows Serial |
|---|---|---|---|
| AIDA64 | Without Root | Yes | Yes (if available) |
| Device Info HW | Without Root | Yes | Partially |
| CPU-Z | Without Root | No | Yes |
| Termux | With access to Shell | Yes (via commands) | Yes (via commands) |
Using third-party software has its advantages: visibility and saving the history of configuration changes. However, you should be careful with applications that require excessive permissions. Trust only trusted, highly rated developers.
Why do some applications not see the Serial Number?
Starting with Android 10, access to permanent device identifiers is blocked for regular applications. Only applications with system privileges or signed with a manufacturer's certificate can read the real serial number directly.
Obtaining the UUID through code for developers
If you are building your own application or testing app code, you may need to call the identifier programmatically. In the development environment Android Studio or directly in Java/Kotlin code, this is implemented through the class Settings.Secure. This method returns the same Android IDthat can be obtained through ADB.
The example code to get the ID string is as follows. You must have an application context to contact the settings content provider.
String androidId = Settings.Secure.getString(getContentResolver(),
Settings.Secure.ANDROID_ID
);
It is important to understand the limitations of this method. When resetting the settings to factory settings (Factory Reset), the value ANDROID_ID changes. In addition, on devices with root access or custom firmware, this identifier can be replaced by the user. For mission-critical tasks such as bank authorization, this method is not recommended as the sole authentication factor.
⚠️ Note: Starting with Android O (8.0), the Android ID value is specific not only to the device, but also to the application + user + device combination. Different applications on the same phone will receive different ID values.
To get a more stable ID that does not change when you reinstall the application, but is reset when you delete data, you can use Instance ID from Firebase or similar services. This is the modern standard for identifying client instances.
Android ID is the best balance between uniqueness and privacy for most user tasks, but it is not constant throughout the entire life cycle of the device.
Access problems and limitations of new versions of Android
Google's privacy policy is becoming stricter every year. In Android versions 11, 12 and later, access to hardware identifiers (IMEI, MAC address, Serial number) is completely closed for regular applications. This is done to protect users from surveillance and the creation of permanent digital profiles without consent.
If your task requires an immutable hardware UUID, you cannot obtain it using standard application tools. The only legal ways are to use privileged system applications (which are only available to manufacturers) or ask the user to manually enter the serial number indicated on the box or in the settings.
In addition, there are “sandboxes” (Scoped Storage) and isolated profiles. In guest mode or when using multiple users on the same device, each profile will generate its own set of IDs. This should be taken into account when debugging multi-user scenarios.
- 🚫 Apps cannot read IMEI without a special exception from the carrier.
- 🔄 Advertising ID can be reset at any time through Google settings, making it unreliable for permanent binding.
- 🛡️ Usage hidden APIs (Hidden API) can lead to blocking of the application in Google Play.
Developers are recommended to reconsider the identification architecture and switch to using authorization tokens or Google accounts, instead of trying to tightly link the application to the hardware of the phone.
For testing on an emulator, remember that the emulator serial number is often generated randomly every time it is launched, unless explicitly set in AVD configuration.
Is it possible to find out the UUID without connecting to a computer?
Yes, you can. Use apps like AIDA64 or look at the serial number in the About Phone section of Settings. However, getting a software Android ID without root access and special utilities inside the phone itself is more difficult; it usually requires entering a USSD code or using an engineering menu that is hidden by manufacturers.
Will the UUID change after flashing the smartphone?
Depends on the type of identifier. The hardware serial number and IMEI are hardwired into memory and do not change. Android ID (software) will be generated again the first time you start the new system. Advertising ID is reset when Google services data is cleared.
Why do applications require access to the phone to obtain the UUID?
Previously, this was necessary to read the IMEI. Nowadays, such requests are often a legacy of old libraries or an attempt to collect telemetry. In modern conditions, most functions do not require access to telephony, and such requests should be viewed with suspicion.
Is a Wi-Fi MAC address a unique device identifier?
Physically yes, but in Android 10+ the system uses a randomized MAC address for each new Wi-Fi network by default. Therefore, using a real MAC address as a permanent UUID to identify a device on the network is now impossible without special rights.