I have a rails app and I’d like to know how can I integrate bpmn with my app? As I understood the bpmn modeler needs a node web server to run, so I have to integrate it by an API? If so the bpmn has a built-in API that I can interact?
You integrate it as you would integrate any client side library into your project.
The bpmn-js starter could help you to better understand what we’re providing and how to integrate it.