Unique Identifier

pub package License: MIT

A Flutter plugin for retrieving a device's unique identifier across Android, iOS, Web, macOS, Linux, and Windows platforms.

Platform Method
🤖 Android ANDROID_ID (scoped to app-signing key, user, and device)
🍎 iOS UIDevice.identifierForVendor
💻 macOS IOPlatformUUID via IOKit (uses kIOMainPortDefault on macOS 12+, falls back to kIOMasterPortDefault for macOS 11)
🐧 Linux Reads /etc/machine-id
🪟 Windows Reads registry value MachineGuid from HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography
🌐 Web Attempts to read UUID from localStorage. If missing/invalid, generates from browser fingerprint. Falls back to random UUID generation. Stores result in localStorage for persistence.

Features

  • Android: Retrieves ANDROID_ID (64-bit hex string scoped to app-signing key, user, and device)
  • iOS: Retrieves identifierForVendor (IDFV unique per vendor)
  • macOS: Retrieves IOPlatformUUID via IOKit framework
  • Linux: Reads /etc/machine-id
  • Windows: Reads MachineGuid from registry
  • Web: Generates/persists UUID via localStorage with fingerprint fallback
  • Cross-platform support with a single API
  • Privacy-compliant device tracking
  • Swift Package Manager support on iOS

Installation

Add the following to your pubspec.yaml:

dependencies:
  unique_identifier_3: ^0.1.0

Then run:

flutter pub get

Import the Package

import 'package:unique_identifier_3/unique_identifier_3.dart';

Usage

Basic Example

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:unique_identifier_3/unique_identifier_3.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _identifier = 'Unknown';

  @override
  void initState() {
    super.initState();
    initUniqueIdentifier();
  }

  Future<void> initUniqueIdentifier() async {
    String identifier;
    try {
      identifier = await UniqueIdentifier.serial;
    } on PlatformException {
      identifier = 'Failed to get Unique Identifier';
    }

    if (!mounted) return;

    setState(() {
      _identifier = identifier;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Unique Identifier Example'),
        ),
        body: Center(
          child: Text('Device ID: $_identifier'),
        ),
      ),
    );
  }
}

Platform-Specific Behavior

Android

  • Uses ANDROID_ID, a 64-bit hexadecimal string
  • Unique to each combination of app-signing key, user, and device
  • Value may change after:
    • Factory reset
    • App-signing key change

iOS

  • Uses identifierForVendor (IDFV)
  • Unique per vendor across all apps from the same vendor
  • Value may change if:
    • All apps from the vendor are uninstalled and reinstalled

macOS

  • Uses IOPlatformUUID via IOKit framework
  • Automatically uses kIOMainPortDefault on macOS 12+ (no deprecation warning)
  • Falls back to kIOMasterPortDefault for compatibility with macOS 11 and earlier

Linux

  • Reads /etc/machine-id
  • Returns the machine ID as stored by the system

Windows

  • Reads MachineGuid from registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography
  • Returns the system's unique machine identifier

Web

  • Attempts to read a UUID from window.localStorage
  • If the value is missing or invalid, it tries to generate one based on browser fingerprint
  • If fingerprinting fails, generates a new UUID using Dart code
  • The newly generated UUID is stored in localStorage for future reuse
  • Ensures the same UUID persists across reloads and sessions
  • Users can manually clear the UUID through browser storage settings

Notes

  • On iOS and Android, the UUID may change after uninstalling and reinstalling the app
  • macOS implementation avoids deprecated APIs on macOS 12+
  • On Web, the UUID persists across reloads and sessions but can be cleared by the user

iOS App Tracking Transparency

If your app uses tracking on iOS, consider requesting App Tracking Transparency (ATT) permission. Below is an example using the app_tracking_transparency package:

import 'package:flutter/material.dart';
import 'package:app_tracking_transparency/app_tracking_transparency.dart';
import 'package:url_launcher/url_launcher.dart';

Future<void> initTrackingTransparency(BuildContext context) async {
  final status = await AppTrackingTransparency.trackingAuthorizationStatus;

  if (status == TrackingStatus.notDetermined || status == TrackingStatus.denied) {
    await showCustomTrackingDialog(
      context,
      'We use tracking to enhance your experience and provide personalized content and ads.',
    );

    await Future.delayed(const Duration(milliseconds: 1000));

    final newStatus = await AppTrackingTransparency.requestTrackingAuthorization();
    if (newStatus == TrackingStatus.notDetermined || newStatus == TrackingStatus.denied) {
      await showSettingsDialog(
        context,
        'Please enable tracking in Settings > Privacy & Security > Tracking.',
      );
    }
  }

  final uuid = await AppTrackingTransparency.getAdvertisingIdentifier();
  if (uuid == '00000000-0000-0000-0000-000000000000') {
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text("Unable to track your device")),
    );
  }
}

Future<void> showCustomTrackingDialog(BuildContext context, String message) async {
  return showDialog<void>(
    context: context,
    builder: (context) => AlertDialog(
      title: const Text('Attention'),
      content: Text(message),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: const Text('Continue'),
        ),
      ],
    ),
  );
}

Future<void> showSettingsDialog(BuildContext context, String message) async {
  return showDialog<void>(
    context: context,
    builder: (context) => AlertDialog(
      title: const Text('Settings Required'),
      content: Text(message),
      actions: [
        TextButton(
          onPressed: () async {
            const url = 'app-settings:';
            if (await canLaunchUrl(Uri.parse(url))) {
              await launchUrl(Uri.parse(url));
            }
            Navigator.pop(context);
          },
          child: const Text('Settings'),
        ),
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: const Text('Not Now'),
        ),
      ],
    ),
  );
}

Bugs & Feature Requests

Please open an issue on GitHub for bugs or feature requests. Pull requests are welcome!

License

This project is licensed under the MIT License.

Libraries

unique_identifier_3