Saving Data Locally with Shared Preferences in Flutter

Introduction

Not every app needs a full database to store user data—sometimes, all you need is a way to persist small, simple values like user preferences, theme modes, or high scores. Flutter’s shared_preferences plugin offers a lightweight, key-value storage solution perfect for these use cases. It allows you to read and write primitive types locally with ease, providing a simple API that integrates seamlessly into any Flutter project.

In this guide, you’ll learn how to set up shared_preferences, save and retrieve values, and manage stored data efficiently. Whether you're building onboarding flows, saving user settings, or implementing feature toggles, this plugin is a must-have in your Flutter toolkit.

Setup

1. Add the dependency in your pubspec.yaml:

   dependencies:
     flutter:
       sdk: flutter
     shared_preferences
   
   

2. Run flutter pub get.

3. Import and initialize the plugin in your Dart code:

   import 'package:flutter/material.dart';
   import 'package:shared_preferences/shared_preferences.dart';
   
   void main() {
     runApp(MyApp());
   }

4. You’ll call SharedPreferences.getInstance() inside async callbacks or state initialization.

Saving Data

Use the shared_preferences API to persist primitive types (String, int, bool, double, List). All setters return a Future.

Future<void> saveUserSettings() async {
  final prefs = await SharedPreferences.getInstance();
  await prefs.setString('username', 'alice123');
  await prefs.setBool('darkMode', true);
  await prefs.setInt('highScore', 42);
}

In this snippet:

• setString('username', 'alice123') stores a user ID.

• setBool('darkMode', true) toggles a theme flag.

• setInt('highScore', 42) tracks a numeric value.

Retrieving Data

Fetching stored values is straightforward. Use default values or null checks if keys are missing.

Future<void> loadUserSettings() async {
  final prefs = await SharedPreferences.getInstance();
  final username = prefs.getString('username') ?? 'Guest';
  final darkMode = prefs.getBool('darkMode') ?? false;
  final highScore = prefs.getInt('highScore') ?? 0;

  print('User: $username, Dark Mode: $darkMode, High Score: $highScore');
}

Here, getString, getBool, and getInt read from local storage. The ?? operator ensures your app won’t crash on a missing key.

Clearing Data

To remove a single entry, call:

await prefs.remove('username');

To wipe all stored preferences (use with caution):

await prefs.clear();

remove targets one key; clear resets your entire persistent local storage for the shared_preferences namespace.

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Conclusion

You’ve now mastered the basics of saving and retrieving simple data using Flutter shared preferences. This approach is perfect for user settings, onboarding flags, or light caching without a full database. For more advanced storage patterns (encrypted storage, structured objects), explore other packages like sqflite or hive.