Next.js example with firebase authentication. Including authentication check at SSR.
npm install
Set up a firebase project
Create an .env file, based on .env example. Fill out your Firebase project properties.
npm run dev
http://localhost:3000/signin -> example signin page http://localhost:3000/user -> example authentication check in 'getServerSideProps'
https://medium.com/@thomasswolfs/next-js-firebase-authentication-including-ssr-1045b097ee18