--- ## Initialization --- This method initializes Synerise.
This method must be called before any other Synerise SDK method and only once during the application's lifecycle.
**Declared In:** lib/main/Synerise.js **Related To:** [Synerise](/developers/mobile-sdk/class-reference/react-native/lifecycle#synerise) [SyneriseInitializer](/developers/mobile-sdk/class-reference/react-native/lifecycle#syneriseinitializer) **Class:** [PromotionsModule](/developers/mobile-sdk/class-reference/react-native/modules#promotions) **Builder Parameters:** | Parameter | Type | Mandatory | Default | Description | | --- | --- | --- | --- | --- | | **withBaseUrl** | string | no | - | Synerise API custom environment base URL | | **withApiKey** | string | yes | - | Synerise Profile (formerly Client) API Key | | **withDebugModeEnabled** | **boolean** | no | - | Enables or disables console logs | | **withCrashHandlingEnabled** | **boolean** | no | - | Enables or disables crash handling | | **withSettings** | **object** | no | - | Settings that have to be configured before Synerise is initialized |
Before version 1.0.0, the `withApiKey` method was called `withClientApiKey`.
**Return Value:** No value is returned. **Example:**
```JavaScript Synerise.Initializer() .withBaseUrl("YOUR_API_BASE_URL") .withApiKey('YOUR_PROFILE_API_KEY') .withDebugModeEnabled(true) .withCrashHandlingEnabled(true) .withSettings({ sdk: { enabled: true }) .init(); ```
## Change Profile API key dynamically --- This method changes a Profile (formerly Client) API key dynamically. **Declared In:** lib/main/Synerise.js **Declaration:** 
public static changeApiKey(ApiKey: string, config?: InitializationConfig | undefined)
Before version 1.0.0, this method was called `changeClientApiKey`.
**Parameters:** | Parameter | Type | Mandatory | Default | Description | | --- | --- | --- | --- | --- | | **apiKey** | string | yes | - | New API key | | **config** | [InitializationConfig](/developers/mobile-sdk/class-reference/react-native/lifecycle#initializationconfig) | no | - | Object for additional initialization settings after the API key change | **Return Value:** No value is returned. **Example:**
```JavaScript Synerise.changeApiKey(apiKey); ```
## Change Profile API Key dynamically with config --- This method changes a Profile (formerly Client) API key dynamically, with additional parameters. It can include a salt for [Simple Profile Authentication](/developers/mobile-sdk/user-identification-and-authorization/simple-authentication) requests. | | **iOS SDK** | **Android SDK** | **React Native SDK** | **Flutter SDK** | | --- | --- | --- | --- | --- | | Introduced in: | 4.19.0 | 5.20.0 | 0.23.0 | 1.3.0 | **Declared In:** lib/main/Synerise.js **Declaration:** 
public static changeApiKey(ApiKey: string, config?: InitializationConfig | undefined)
Before version 1.0.0, this method was called `changeClientApiKey`.
**Parameters:** | Parameter | Type | Mandatory | Default | Description | | --- | --- | --- | --- | --- | | **apiKey** | string | yes | - | New API key | | **config** | [InitializationConfig](/developers/mobile-sdk/class-reference/react-native/lifecycle#initializationconfig) | no | - | Object for additional initialization settings after the API key change | **Return Value:** No value is returned. **Example:**
```JavaScript Synerise.changeApiKey(apiKey); ```