data_save

One API for storing small values in Flutter applications. data_save uses SharedPreferences on native platforms and persistent cookies on Flutter Web.

Features

• Supports String, bool, int, and double values.
• Uses URI encoding for safe Unicode and delimiter storage on the web.
• Uses host-only cookies with SameSite=Lax and Secure on HTTPS.
• Supports Flutter Web builds compiled to JavaScript or WebAssembly.

Installation

dependencies:
  data_save: ^0.4.0

Usage

Initialize the library before reading or writing values:

import 'package:data_save/DataSave.dart';
import 'package:flutter/material.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await DataSave.init();
  runApp(const MyApp());
}

Store and retrieve values:

await DataSave.setString('name', 'Sara');
await DataSave.setBool('darkMode', true);
await DataSave.setInt('launchCount', 4);
await DataSave.setDouble('volume', 0.75);

final name = DataSave.getString('name');
final darkMode = DataSave.getBool('darkMode');
final launchCount = DataSave.getInt('launchCount');
final volume = DataSave.getDouble('volume');

Remove stored values:

await DataSave.removeAll();

Larger strings

Use the large-string API for JSON and other values that can exceed the cookie limit. It uses localStorage on web and the same SharedPreferences storage as the normal API on native platforms:

await DataSave.setLargeString('economicCalendar', jsonString);

final jsonString = DataSave.getLargeString('economicCalendar');

await DataSave.remove('economicCalendar');
await DataSave.removeAllLarge();

On web, removeAll() clears both cookies and the origin's entire localStorage. On native platforms, normal and large-string methods use the same SharedPreferences storage.

Web behavior

Web values are stored as first-party cookies for 90 days. Browser cookie limits apply, so this package is intended for small values rather than documents or large JSON payloads.

Cookies created in browser code cannot use the HttpOnly attribute. Do not use this package to store passwords, private keys, or long-lived authentication secrets.