Organizing Express API

src/
	 ├── app.js --- app entry point
	 ├── /api --- controller layer: api routes
	 ├── /config --- config settings, env variables
	 ├── /services --- service layer: business logic
	 ├── /models --- data access layer: database models
	 ├── /scripts --- miscellaneous NPM scripts
	 ├── /subscribers --- async event handlers
	 └── /test --- test suites

src/
		|- controllers/ -> logic before saving to the db, check permission, etc..
		|- db/
			|-- models/ -> the models
			|-- config/ -> config about the db, connection to the db etc
			|-- migrations/ -> all the migrations file for the db
		|- helpers/ -> helpers function like sum, total, pluralize, etc
		|- routes/ -> all the rest api route, where they take a controller as callback
		|- services/ -> stripe, aws s3 etc
		|- test -> all your test
		|-package.json -> all your dependencies
		|-index.js -> where everything start, your server instance etc

src/
		|- api/ --- everything related to routes
			|- controllers/ --- valiadate data
			|- models/ --- models and schemas
			|- helpers/ --- generic helpers functions that maybe used in many places
			|- services/ --- business logic, data transforms and calls to the database
			|- routes/ --- routes
			|- middlewares/ --- routes
			|- validation/ ---
		|-- config/ --- config files
		|- test
		|-package.json
		|-index.js

test/
	src/
		|- api/ --- everything related to routes
			|- controllers/ --- valiadate data
			|- models/ --- models and schemas
			|- helpers/ --- generic helpers functions that maybe used in many places
			|- services/ --- business logic, data transforms and calls to the database
			|- routes/ --- routes
			|- middlewares/ --- routes
			|- validation/ ---
		|-- config/ --- config files
		|-package.json
		|-index.js