Left to our own devices. — Ethan Marcotte
Your website’s only as strong as the weakest device you’ve tested it on.
BenjaminKeen.com
A bookmarklet version of that handy multiple-iframe page I linked to the other day. Even more useful for testing responsive designs!
Related links
Emmet Re:view — fast and easy way to test responsive design in multiple viewports
It’s no substitute for testing with real devices, but the “device wall” view in this Chrome plug-in is a nifty way of getting an overview of a site’s responsiveness at a glance.
Responsive design testing tool – Viewport Resizer
A handy little bookmarklet for quickly checking how a site might look at different screen sizes, and you can customise it to use whichever screen sizes you like.
embedresponsively.com
Here’s the CSS and markup you need to make third-party iframes responsive. Handy!
Responsive Inspector
A handy plugin for Chrome that always you to inspect media query breakpoints and take screenshots at any of them.