Options in Flutter to get the Unique User or Device Identifier

No matter the type of Flutter applications you develop that involves a backend – you will most likely need a unique user or device identifier. Different approaches may be suited for different use cases, such as identifying devices for analytics, preventing multiple sign-ins, or maintaining user sessions. Here are some common methods:

1. Firebase Installation ID

Firebase can generate a unique identifier for installations of your app, useful for analytics and user behavior tracking.

Add dependencies in `pubspec.yaml`:

dependencies:
firebase_core: latest_version
firebase_installations: latest_version

Retrieve Installation ID:

import ‘package:firebase_core/firebase_core.dart’;
import ‘package:firebase_installations/firebase_installations.dart’;

Future getFirebaseInstallationId() async {
await Firebase.initializeApp();
final String installationId = await FirebaseInstallations.instance.getId();
print(‘Firebase Installation ID: $installationId’);
}

2. `device_info_plus` Package

The `device_info_plus` package allows you to gather information about the device, including Android and iOS details. However, a true unique device identifier isn’t directly provided by this package.

import ‘package:device_info_plus/device_info_plus.dart’;

Future getDeviceIdentifier() async {
final DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();

if (Platform.isAndroid) {
final AndroidDeviceInfo androidInfo = await deviceInfo.androidInfo;
print(‘Android Device ID: ${androidInfo.androidId}’);
} else if (Platform.isIOS) {
final IosDeviceInfo iosInfo = await deviceInfo.iosInfo;
print(‘iOS Device ID: ${iosInfo.identifierForVendor}’);
}
}

3. `unique_identifier` Package

This package directly provides a unique identifier for only – Android and iOS devices.

import ‘package:unique_identifier/unique_identifier.dart’;

Future getUniqueIdentifier() async {
String? uniqueId;

try {
uniqueId = await UniqueIdentifier.serial;
} on PlatformException {
print(‘Failed to get unique identifier’);
}

print(‘Unique Identifier: $uniqueId’);
}

4. Device_uuid

Again option that targets only the mobile devices: https://pub.dev/packages/device_uuid/example

5. Custom UUID Generation

If none of the above methods fit your needs, you can generate a custom UUID and store it in local storage (like `shared_preferences`) or secure store if you like higher security – to uniquely identify your user at the app level. I’ve written similar article: https://programtom.com/dev/2021/02/24/how-to-generate-guid-java-php-flutter/

Add dependencies in `pubspec.yaml`:

dependencies:
shared_preferences: latest_version
uuid: latest_version

Generate and Store UUID:

import ‘package:shared_preferences/shared_preferences.dart’;
import ‘package:uuid/uuid.dart’;

Future generateAndStoreUUID() async {
final sharedPreferences = await SharedPreferences.getInstance();
String? uuid = sharedPreferences.getString(‘user_uuid’);

if (uuid == null) {
uuid = Uuid().v4();
await sharedPreferences.setString(‘user_uuid’, uuid);
}

print(‘UUID: $uuid’);
}

Choosing the right approach depends on your specific requirements and constraints around privacy, security, and platform-specific behaviors. Always make sure to comply with relevant privacy laws and guidelines.