On your mobile device's browser (any will work), navigate to http://<Local IP Address>:<port number> . For example, if I was serving on localhost:8080 and my local IP address is 123.45. 67.890, on my mobile device's browser I would navigate to http://123.45.67.890:8080 .
How can I open localhost?
Usually, you can access the localhost of any computer through the loopback address 127.0. 0.1. By default, this IP address references a server running on the current device.
How do I find localhost on my iPhone?
Running localhost
Navigate to http://yourname.local:8000 on your phone and you're all set!