The most important thing is that you separate the different layers of the app so that you can refactor later. Using Spring is a good way to keep that separation

The most important thing is that you separate the different layers of the app so that you can refactor later. Using Spring is a good way to keep that separation. The frontend layer needs to be agnostic of how the middle layer is implemented, and the middle layer agnostic of the backend. JSON and REST are universal, so if everything communicates using that, you are in good shape if you ever partner with other companies or get acquired.