An interactive viewer to see and test how digital products respond to material design breakpoints across desktop, mobile, and tablet.
https://design.google.com/articles/introducing-resizer/
Basically Resizer is a website that lets you look at how your responsive design is going to look across multiple screens. It provides instant access to a number of different screen sizes and orientations in a way that is a lot less fussy than resizing browser windows. Give it a try and enter the address of any website to see how the layout responds at different break points.