Initialize the Firebase Admin with Next.js

Learn how to use Firebase on the server with Next.js

ยท2 min read

The Firebase Admin package is a way to use Firebase on NodeJS, thus allowing us to write backend code with the various Firebase packages such as Auth, Firestore, Storage, and so on.

To use Firebase with a Next.js API function, we have to initialize the Firebase Admin. Let's see how it's done:

Firebase configuration

First, we have to store and retrieve the Firebase configuration for our project.

To do so, we can use the Next.js environment variables by creating a .env file in the root folder, and making sure to fill the values below correctly:


Once it's done, we can create a function that accepts the following interface and returns the Firebase admin app:

interface FirebaseAdminAppParams { projectId: string; clientEmail: string; storageBucket: string; privateKey: string; }

The snippet below is everything you need to create an admin app using Firebase:

import admin from 'firebase-admin'; function formatFirebasePrivateKey(key: string) { return key.replace(/\\n/g, '\n'); } export function createFirebaseAdminApp(params: FirebaseAdminAppParams) { const privateKey = formatFirebasePrivateKey(params.privateKey); // if already created, return the same instance if (admin.apps.length > 0) { return; } // create certificate const cert = admin.credential.cert({ projectId: params.projectId, clientEmail: params.clientEmail, privateKey, }); // initialize admin app return admin.initializeApp({ credential: cert, projectId: params.projectId, storageBucket: params.storageBucket, }); }

Let's assume you created a Next.js API function and want to create a Firebase admin app to be able to use Firestore, you can do the following:

import { createFirebaseAdminApp } from './initialize-firebase-admin-app'; import { getFirestore } from 'firebase-admin/firestore'; async function initializeAdmin() { const params = { projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID, clientEmail: process.env.FIREBASE_CLIENT_EMAIL, storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET, privateKey: process.env.FIREBASE_PRIVATE_KEY }; return createFirebaseAdminApp(params); } export default function getTeams( req: NextApiRequest, res: NextApiResponse, ) { // initialize admin await initializeAdmin(); // now we can use the Firebase packages! const firestore = getFirestore(); const { docs, size } = await firestore.collection('teams').get(); const teams = => return res.send(teams); }