Using Firebase

Install the SDK

After you have created your Expo project, you can install the Firebase JS SDK using the following command:

Initialize the SDK in your project

To initialize the Firebase instance in your Expo project, you must create a config object and pass it to the initializeApp() method imported from the firebase/app module.

The config object requires an API key and other unique identifiers. To obtain these values, you will have to register a web app in your Firebase project. You can find these instructions in the Firebase documentation.

After you have the API key and other identifiers, you can paste the following code snippet by creating a new firebaseConfig.js file in your project's root directory or any other directory where you keep the configuration files.

import { initializeApp } from 'firebase/app';

// Optionally import the services that you want to use
// import {...} from "firebase/auth";
// import {...} from "firebase/database";
// import {...} from "firebase/firestore";
// import {...} from "firebase/functions";
// import {...} from "firebase/storage";

// Initialize Firebase
const firebaseConfig = {
  apiKey: 'api-key',
  authDomain: 'project-id.firebaseapp.com',
  databaseURL: 'https://project-id.firebaseio.com',
  projectId: 'project-id',
  storageBucket: 'project-id.appspot.com',
  messagingSenderId: 'sender-id',
  appId: 'app-id',
  measurementId: 'G-measurement-id',
};

const app = initializeApp(firebaseConfig);
// For more information on how to access Firebase in your project,
// see the Firebase documentation: https://firebase.google.com/docs/web/setup#access-firebase

You do not have to install other plugins or configurations to use Firebase JS SDK.

Firebase version 9 and above provide a modular API. You can directly import any service you want to use from the firebase package. For example, if you want to use an authentication service in your project, you can import the auth module from the firebase/auth package.

Troubleshooting tip: If you encounter issues related to authentication persistence with Firebase JS SDK, see the guide for setting up persistence to keep users logged in between reloads.

Configure Metro

If you are using Firebase version 9.7.x and above, you need to add the following configuration to a metro.config.js file to make sure that the Firebase JS SDK is bundled correctly.

Expo CLI uses Metro to bundle your JavaScript code and assets, and add support for more file extensions.

Start by generating the template file metro.config.js in your project's root directory using the following command:

Then, update the file with the following configuration:

const { getDefaultConfig } = require('@expo/metro-config');

const defaultConfig = getDefaultConfig(__dirname);
defaultConfig.resolver.sourceExts.push('cjs');

module.exports = defaultConfig;

Install expo-dev-client

Since React Native Firebase requires custom native code, you need to install the expo-dev-client library in your project. It also allows configuring any native code required by React Native Firebase using Config plugins without writing native code yourself.

To install expo-dev-client, run the following command in your project:

Install React Native Firebase

To use React Native Firebase, it is necessary to install the @react-native-firebase/app module. This module provides the core functionality for all other modules. It also adds custom native code in your project using a config plugin. You can install it using the following command:

At this point, you must follow the instructions from React Native Firebase documentation as it covers all the steps required to configure your project with the library.

Once you have configured the React Native Firebase library in your project, come back to this guide to learn how to run your project in the next step.

Run the project

If you are using EAS Build, you can create and install a development build on your devices. You do not need to run the project locally before creating a development build. For more information on creating a development build, see the section on installing a development build.