I know most of you guys here already use this tool from google to test if your site is mobile friendly, https://www.google.com/webmasters/to...bile-friendly/

However, I want to give you guys a relevant tool of how your site performs on mobile search using your desktop.

If you are using an updated version of Google Chrome you can check this out. I'm not sure if it works with Firefox since I don't have an updated version but Chrome will do.

Here's a complete guide you can follow
https://developer.chrome.com/devtools/docs/device-mode