For the use case you originally stated I think google analytics or a 3rd party service to count visitors.
When it comes to a login feature, Netlify Identity is in it’s early stages, and only allows for things like Role-based access control with JWT | Netlify Docs
If this is something your interested in, then I’ll link to a few discussions where you will be able to learn more about Role based redirects and how they work.
Kyle.