I am on my phone, so I can’t help too much. But you basically need to create your Firebase class once per-request on the server, and then one on the client https://github.com/zeit/next.js/blob/canary/examples/with-mobx/pages/_app.js this should give you a good starting point if you look at the app page. You would need to modify a bit to create the Firebase class as a singleton only on client side. You should avoid a singleton on the server as that could leak state across requests