My startup's experience was similar. Our core is an Angular app to a Django backend API. Django and Rails are roughly the same level of maturity. The approac

My startup's experience was similar. Our core is an Angular app to a Django backend API. Django and Rails are roughly the same level of maturity. The approach that's worked best for us is to keep all of the business logic and CRUD-y stuff in this Django base, then spin out dedicated microservices in the special cases e.g. CPU-bound tasks. I think most startups end up with a similar architecture.