---
title: Client Initialization
description: Initialization Firebase with the client method.
---

# Client Initialization

> The default firebase app instance can not be initialized via JS. After following the iOS & Android installation guides and correctly setting up your google services plist/json files, the default app is automatically initialized and available for use in react-native-firebase.

App initialization in React Native Firebase is, for the most part, the same as the web SDK, with only a few minor differences.

## Supported Modules

Only some modules on the official Firebase native SDK's support multiple apps, they are as follows:

- Authentication
- Database
- Firestore
- Functions
- Instance ID
- Storage
- ML Kit Natural Language
- ML Kit Vision

For further information, view [Firebase Documentation for Multiple Projects](https://firebase.google.com/docs/web/setup#multiple-projects).

## Initialize apps via JavaScript

### Cross Platform Example

```javascript
import { Platform } from 'react-native';
import firebase from '@react-native-firebase/app';

// pluck values from your `GoogleService-Info.plist` you created on the firebase console
const iosConfig = {
  clientId: 'x',
  appId: 'x',
  apiKey: 'x',
  databaseURL: 'x',
  storageBucket: 'x',
  messagingSenderId: 'x',
  projectId: 'x',

  // enable persistence by adding the below flag
  persistence: true,
};

// pluck values from your `google-services.json` file you created on the firebase console
const androidConfig = {
  clientId: 'x',
  appId: 'x',
  apiKey: 'x',
  databaseURL: 'x',
  storageBucket: 'x',
  messagingSenderId: 'x',
  projectId: 'x',

  // enable persistence by adding the below flag
  persistence: true,
};

const kittensApp = firebase
  .initializeApp(
    // use platform-specific firebase config
    Platform.OS === 'ios' ? iosConfig : androidConfig,
    // name of this app
    'kittens',
  )
  .then(app => console.log('initialized apps ->', firebase.apps));
```

## Initialize apps via Android/iOS native code

If you're familiar with native code you can create apps natively also (or if you are already initializing additional apps natively on app boot) - these apps automatically become available for use inside RNFirebase.

For example, if you created an app natively called `dogs` then the following would work:

```javascript
import firebase from '@react-native-firebase/app';

const dogsApp = firebase.app('dogs');
```

## Deleting an app instance

Firebase App instances can be deleted via `app.delete()`.

```js
await firebase.app('kittens').delete();
```

> Note that it's not possible to delete the `default` app instance.