# SDK Opt-out

Opt-out is a feature that stops collecting a user's data. It is used to comply with privacy regulations or to respond to a user's request to stop data collection.

{% hint style="info" %}
Even in an opt-out state, SDK features such as A/B Tests, Feature Flags, and In-App Messages continue to work normally.
{% endhint %}

### How to Configure Opt-out

Opt-out can be configured in two ways:

* **Configure at initialization**: Set `optOutTracking` in the SDK initialization config.
* **Configure at runtime**: Change the opt-out state while the app is running using the `setOptOutTracking()` method.

### State Management

{% hint style="warning" %}
The SDK manages the opt-out state only in memory. When the app restarts, it resets to the value set in the initialization config.
{% endhint %}

The opt-out state changed via `setOptOutTracking()` is not persisted when the app restarts. When the app restarts, the `optOutTracking` value set in `HackleConfig` is applied.

#### Persistence Management

To persist a user's opt-out setting across app restarts, **you must manage it persistently in your app**.

**Recommended Implementation Flow**

1. When a user changes their opt-out setting, save the state to the app's persistent storage.
2. When the app starts, read the opt-out state from storage and set it in the SDK initialization config.
3. When the state changes while the app is running, update both the storage and the SDK.

**Persistent Storage Examples by Platform**

| Platform           | Persistent Storage                              |
| ------------------ | ----------------------------------------------- |
| iOS                | UserDefaults                                    |
| Android            | SharedPreferences                               |
| JavaScript / React | localStorage                                    |
| React Native       | AsyncStorage or MMKV                            |
| Flutter            | SharedPreferences (shared\_preferences package) |

{% hint style="info" %}
For specific usage of the opt-out API and code examples for persistence management, refer to each SDK's opt-out documentation.
{% endhint %}


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