# Opt-out

When Opt-out is enabled, the SDK stops sending all events.

{% hint style="info" %}
Flutter SDK is built on top of Android SDK and iOS SDK.
{% endhint %}

## Configure at Initialization

```dart
import "package:hackle/hackle.dart";

HackleConfig config = HackleConfigBuilder()
    .optOutTracking(true)
    .build();

await HackleApp.initialize(YOUR_APP_SDK_KEY, hackleConfig: config);
```

## Runtime Opt-out Control

```dart
await HackleApp.setOptOutTracking(true);
await HackleApp.setOptOutTracking(false);
bool isOptOut = await HackleApp.isOptOutTracking();
```

## Persistence Management

{% hint style="warning" %}
The Opt-out state changed at runtime is reset to the value set in the initialization Config when the app restarts.

To persist the state across app restarts, you must implement your own save and restore logic.
{% endhint %}

```dart
import 'package:shared_preferences/shared_preferences.dart';
import 'package:hackle/hackle.dart';

Future<void> saveOptOutState(bool optOut) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setBool('hackle_opt_out', optOut);
    await HackleApp.setOptOutTracking(optOut);
}

Future<HackleConfig> getOptOutConfig() async {
    final prefs = await SharedPreferences.getInstance();
    final optOut = prefs.getBool('hackle_opt_out') ?? false;
    return HackleConfigBuilder()
        .optOutTracking(optOut)
        .build();
}

final config = await getOptOutConfig();
await HackleApp.initialize(YOUR_APP_SDK_KEY, hackleConfig: config);
```


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