Here are 6 awesome responsive design bookmarklets — makes it easy to try out various sizes right in your browser!

Viewport resizer

Viewport resizer is a browser-based tool to test any website’s responsiveness. Just save the bookmarklet, go to the page you want to test, click on your created bookmarklet and check all kinds of screen resolutions of the page.

Media Query Bookmarklet

The mediaQuery bookmarklet gives a visual representation of the current viewport dimensions and most recently fired media query.

Responsive Design bookmarklet

This is a simple script that lets you view any webpage in multiple screen sizes, simulating the viewport of different devices. It works by generating a custom bookmarklet containing whatever screen dimensions you’re interested. You can then just click the bookmark to view any current webpage in a variety of sizes.

RWD bookmarklet

Responsive Design bookmarklet is a handy tool for responsive design testing.

Resizer

Resizer allows you to quickly change the dimensions of a webpage to test responsive design.

FitWeird

FitWeird helps you add breakpoints when things get weird. It’s about as dumb as it gets. Resize your window, it tells you dimensions in PX and EM.