You can use it as a standalone backend or you can just use it as a router / renderer "web backend" but then still have an API off somewhere else. That API could

You can use it as a standalone backend or you can just use it as a router / renderer "web backend" but then still have an API off somewhere else. That API could be a monolith, a bunch of microservices, power multiple front ends, be a legacy system etc etc. When I said backend above I meant company backend / API / services.