Maybe 80, maybe not, it will run on port $PORT which is provided at runtime by Heroku. Practically you do not need to worry about it, Heroku will take care to r

Maybe 80, maybe not, it will run on port $PORT which is provided at runtime by Heroku. Practically you do not need to worry about it, Heroku will take care to route the request from port 80 on the outside to port $PORT at the dyno level.