I've inherited a monolithic Rails app for an MVP product. We're planning to slowly migrate away from RoR to build the remaining parts of the app. App requirements: - Video streaming w/ audio - Real time chat - User authentication & roles - Payment system Performance, scalability, and attracting dev talent(s) are important to our team.
I see it's been some time since this was posted, but I'm glad you are migrating to Next.js 🎉!
Me personally, I would run an Express.js backend so that frontend and backend logics don't feel blurred, especially if you want to attract more developers to your project. Keeping frontend separated from the backend makes for a healthier workspace ecosystem and often confuses people less. Furthermore, implementation is a lot easier and later on as you move from RoR to an Express.js server there won't be too much confusion as to how certain parts mesh together.
Based on the features you're looking at I would consider using websockets (WSS or Socket.IO) for the chat application or rolling that with features from WebRTC, which you would need to support video streaming anyways. For authentication you could look at Auth0 which has some very nice libs for authentication or you could rig up your own stitching individual OAuths (Google, Facebook, etc.) along with a simple User/Pass signup that you manage in your database. For payment I would consider using Stripe, it's very popular in the JS ecosystem right now, has lots of documentation and features, and is also pretty cost-effective.
I know it's been some time since you have posted this and you have already made some decisions, but if you (or anyone else reading this) has any question feel free to let me know :)
Moving from Rails will reduce development velocity (if you want to have easy support and update the app) and will require more skilled (expensive) developers to support it.
Without previous experience (5+ years) do not suggest moving to node.js. That code will easily become hard to learn and support.
You always can implement microservices with Ruby, but this approach should be considered only after Series-A and when you will have more than 5 developers and dedicated SRE/DevOps.