Sounds like a perfect application for an MVC framework. RoR is the most popular, but I would recommend Phoenix (and Elixir) for your project, specifically becau

Sounds like a perfect application for an MVC framework. RoR is the most popular, but I would recommend Phoenix (and Elixir) for your project, specifically because you mentioned that scaleability was important to you, and Elixir has a very powerful concurrency and scaling model, as well as a bunch of other features from Phoenix that would benefit your project.