react-boilerplate/docs/testing/remote-testing.md

Remote testing

npm run start:tunnel

This command will start a server and tunnel it with ngrok. You'll get a URL that looks a bit like this: http://abcdef.ngrok.com

This URL will show the version of your application that's in the build folder, and it's accessible from the entire world! This is great for testing on different devices and from different locations!