If you wanted something where you could get pretty far without spending any money, Cloudflare Workers + Durable Objects would be an interesting path. You would

If you wanted something where you could get pretty far without spending any money, Cloudflare Workers + Durable Objects would be an interesting path. You would have to implement some of the functionality yourself, but there are some examples. Like this example chat app: https://github.com/cloudflare/workers-chat-demo/blob/master/src/chat.mjs https://github.com/cloudflare/workers-chat-demo/blob/master/... It supports private chat rooms, which is somewhat analogous to a pub sub topic.