Splitting the beta program site

I have a website and I need to create a beta version for it. The idea is split into two separate sites, one running a stable app and the other a beta app.

The problem is that the URL to access stable or beta apps must be the same and based on some rules like header value, request body or request parameter, the request will be redirected to the correct site.

I've tried Apache's mod_proxy module, but it doesn't have the ability to create specific rules like the ones I need.

Could you help me? Any ideas how to implement this?