ZenovayTools

Responsive Breakpoint Tester

Test how any URL looks at different screen sizes. Preview mobile, tablet, desktop, and custom breakpoints.

Some websites block iframe embedding via X-Frame-Options or CSP headers. If a site appears blank, it may not allow iframe loading.

How to Use Responsive Breakpoint Tester

  1. 1Enter the URL of the website you want to test.
  2. 2Select a preset breakpoint: mobile, tablet, or desktop.
  3. 3Or enter custom width and height dimensions.
  4. 4Preview how the website renders at the selected viewport size.
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Frequently Asked Questions

How does the responsive tester work?▾
It loads the target URL in an iframe at different viewport sizes, simulating how your website looks on various devices. The iframe width matches the preset device width.
Why does the iframe show a blank page or error?▾
Many websites set X-Frame-Options or Content-Security-Policy headers that prevent them from being loaded in iframes. This is a security measure. Try testing with your own websites or sites that allow iframe embedding.
Can I test custom viewport sizes?▾
Yes. Enter any custom width and height in pixels using the input fields at the top. You can also switch between preset device sizes.
Is this the same as browser DevTools?▾
This tool provides a quick visual overview of multiple breakpoints at once. For more detailed responsive testing, browser DevTools offer additional features like touch simulation and network throttling.
Is any data sent to a server?▾
No. The tool loads the website directly in an iframe within your browser. No URLs or data are sent to any external server.
Can I use this tool on my phone?▾
Yes, the responsive tester works in mobile browsers, though viewing multiple viewport sizes is easier on a larger screen. On mobile, you can test one viewport size at a time.
What device presets are available?▾
The tool includes presets for common devices like iPhone, iPad, and popular Android phones. You can also enter any custom width and height to test specific breakpoints used in your CSS.