Use Firebase Admin SDK inside a Next.js project.

firebaseAdmin.js

// I usually put this in config/firebaseAdmin.js
import * as admin from 'firebase-admin'

// You need your account service key json file inlined in .env
let serviceAccount = JSON.parse(process.env.FIREBASE_ACCOUNTKEY)
let config = {
  credential: admin.credential.cert(serviceAccount)
}

export default !admin.apps.length ? admin.initializeApp(config) : admin;