Frontend : AngularJS
Backend: Play framework (Java/Scala) + MySQL + Nginx (load balancer) + Redis (cache), deploy all these pieces with docker (highly recommended)
- if your data model not complicated, you can also just use Redis.
- try use websocket for push tech.
FYI, This is a general bootstrapping stack for basically everything, to have different pivoting on the stack, you need expose more business knowledge about your website.