Recently I stumbled upon Responsively that allows me to check a website from different device screen sizes and it’s so easy to use. You can customize the devices you need to test a website for and see them simultaneously. The actions you do on the devices are mirrored on the others, and you can disable this too if needed. No more using the developer tools to check for multiple devices.
Edit: I’m using Pixefy now inside the browser instead. I had moments where Responsively was glitching.