When I later pulled up my site on my monitor’s wide screen, I discovered that I’d never actually accounted for screens wider than the 13” laptop that I’d been programming on, either.

After deploying my personal website for example, I was surprised to find that the version of my site I saw in my iPhone’s browser looked quite different from the local DevTools version I’d spent hours with, tweaking media query after media query. The Chrome DevTools Device Toolbar is a great tool that saves a lot of time, but it’s not perfect.

You may have known Chrome DevTools enables you to test the look and feel of your web application on differently-sized devices, but did you know that you can also use run localhost on any device that can connect to the internet? As you run localhost:3000 (or whichever port) on your local machine, your phone and tablets can run your program in real time for developing and testing on mobile.