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Responsive Design Tester

See one page at several device sizes at once. Enter a URL, choose devices, and compare layouts side by side.

Try:

Devices

Zoom

Enter a page above to see it on phones, tablets and desktops side by side.

Each frame is the real page at that screen width, so media queries and layouts respond like they do on a device. It doesn’t emulate touch, the device’s user agent, or pixel density.

If a frame stays blank, the site forbids being shown inside other pages (its X-Frame-Options or CSP frame-ancestors header). Use the pop-out button on a device to open the page in a window of that size instead. Your own local sites (http://localhost:…) work too.

More in QA & Testing

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Check Your Layout at Every Screen Size

Responsive bugs hide between breakpoints. Load your page in frames the size of popular phones, tablets and desktops, rotate them, add a custom size and compare them side by side. Local development servers work too.

What you can do

  • Eleven device presets from a 280px folded phone to 1920px desktop.
  • Rotate any device between portrait and landscape.
  • Custom width and height, plus zoom to fit everything on screen.
  • Works with http://localhost:3000 and other local sites, and can pop a device size out into its own window.

Good to know

  • Each frame is the real page at that width, so CSS media queries respond like on a device. Touch input, device pixel ratio and the mobile user agent are not emulated.
  • Some sites refuse to be shown inside other pages (X-Frame-Options or CSP frame-ancestors). For those, use the pop-out button.
  • Pages are loaded directly by your browser. Nothing passes through our servers.

Frequently asked questions

How do I test my site on different screen sizes?

Enter the URL, pick the devices, and each one shows your page at its width and height.

Why is a frame blank?

The site probably forbids being embedded in other pages. Use the pop-out button to open it in a window of that size.

Can I test localhost?

Yes. Enter something like http://localhost:3000 and your own dev server appears in every frame.

Does it emulate touch or the mobile browser?

No. It resizes the real page, which is ideal for layout and breakpoints. For touch or user-agent checks use your browser’s device tools.