node.js - Can I use socket.io with a php based free heroku app?

one text

Solution:

It's not currently possible to have a websockets server running alongside a PHP app on Heroku. Only web dynos can receive HTTP traffic on Heroku, and only on the specified port.

https://help.heroku.com/8R7OO0ZV/can-i-run-a-websockets-server-using-php-on-heroku