Does this show exactly how the site behaves on a real device?

It's close — the iframe uses the same viewport dimensions as the preset, so responsive CSS breakpoints render correctly. It doesn't emulate touch input, device pixel ratio or user-agent, so treat it as a quick visual check, not a full device emulator.

Why does a site fail to load in the preview?

Some sites block being embedded in an iframe (via an X-Frame-Options or CSP header) as an anti-clickjacking measure — that's a restriction the site itself sets, not something this tool can bypass.

Does this tool track or log the URLs I preview?

No — the URL is only used to load the iframe in your browser.

Viewport Tester

Preview a website at common device widths — phone, tablet, laptop and desktop.

Top ad slot

URL to preview

Device

Related tools

Bottom ad slot

How it works

1
Enter a URL

The site you want to preview.
2
Pick a device preset

iPhone SE/14 Pro, Pixel 7, iPad Mini/Pro, Laptop or Desktop.
3
View it live

The site loads in an iframe sized to that preset's width and height.

FAQ

Does this show exactly how the site behaves on a real device?: It's close — the iframe uses the same viewport dimensions as the preset, so responsive CSS breakpoints render correctly. It doesn't emulate touch input, device pixel ratio or user-agent, so treat it as a quick visual check, not a full device emulator.
Why does a site fail to load in the preview?: Some sites block being embedded in an iframe (via an X-Frame-Options or CSP header) as an anti-clickjacking measure — that's a restriction the site itself sets, not something this tool can bypass.
Does this tool track or log the URLs I preview?: No — the URL is only used to load the iframe in your browser.