Architecture
We use a micro-service architecture.
Nginx service is our reverse proxy. All requests to access the application go through here.
UI service is the entrance door for users, it is the interface that will allow them to use the entire application.
API service is the BackEnd. It is the brain of the application, responsible for managing user access and actions.
Engine service is the one who calculates the recommendations for the users.
These two diagrams below can help you to understand how these services are organised.
Macro architecture

Functional macro architecture

Tip
You will find more information about each services on their owns pages.