Ask HN: What is your recommended stack for real time chat?

If you were building a new real time chat app like discord or slack in 2022, what would your tech stack look like?

I’m in this situation right now and am exploring options that will help me avoid reinventing the wheel.

My plan was to just build it from scratch using socket.io.

While looking at options like using matrix or using a third party tool like pusher, I thought to check here to see what others have done.