Breakpoint Tester is used to quickly and easily test the responsiveness of a website at various breakpoints. Breakpoint Tester ships with some sensible defaults to get you started off right but you're more than welcome to use your own custom breakpoints. Breakpoint Tester uses the default media queries that ship with Bootstrap 3 as a baseline for it's breakpoint presets which are: 480px (Mobile) 768px (Tablet) 992px (Laptop) 1200px (Desktop) Breakpoint Tester is open source and licensed under the MIT license. You are more than welcome to contribute to development, the project can be found on GitHub: https://github.com/JeffreyHyer/BreakpointTester If you run into any issues or would like to request a new feature please do so either via the "Send Feedback" link in the Chrome Webstore or by opening a new GitHub issue. Feedback is both welcome and encouraged!