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A Responsinator alternative that finds the bugs

Responsinator is a free site that loads your page in frames sized like common phones and tablets, upright and sideways: a quick look at a mobile layout. It loads the page in iframes, so sites that block framing don’t show, and it doesn’t tell you what’s wrong. UICheck opens the page at each size in a real browser, measures it and lists every problem with a screenshot and a fix.

Side by side

What it isUICheck: Automatic responsive and layout QA for any URLResponsinator: Free preview of a site in device-sized frames
How it rendersUICheck: A real browser at each screen size (Chrome, Safari’s WebKit, Firefox)Responsinator: iframes in your own browser
Sites that block framingUICheck: WorkResponsinator: Don’t load
Finds bugsUICheck: Yes, automatically, with the element and the fixResponsinator: No, you look for them
Screen sizesUICheck: Up to 7 plus a 320–1920px breakpoint sweep (Lens and Prism)Responsinator: A fixed set of devices
ReportUICheck: Share link, PDF and ExcelResponsinator: None

Based on public information, checked October 2026. Something changed? Tell us and we’ll update it.

Choose Responsinator if

  • You want a quick free glance at a page in device frames

Choose UICheck if

  • You want to know what’s broken, not just see it
  • Your site doesn’t load in frames
  • You need current device sizes, Safari and Firefox, or a report

Or use both

A glance in Responsinator is fine while building; run UICheck before launch to be sure nothing is broken.

Also compare

Try UICheck next to Responsinator

Free account, 5 checks a day, no card. Paste a URL and see what it finds in about a minute.

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