Responsive Design Tester

Test layouts at different breakpoints with device presets and custom viewports

Note: Some websites may block iframe embedding for security reasons.

Device Presets

Custom Dimensions

Orientation

Preview

Help

How to Use This Tool
  • Test a URL: Enter a website URL and click "Load" to preview it
  • Test HTML: Switch to "Test HTML" tab and paste your HTML code
  • Device Presets: Click any device button to instantly resize to that device
  • Custom Size: Enter specific width and height for testing custom breakpoints
  • Orientation: Toggle between portrait and landscape modes
Common Breakpoints
  • 320px: Small mobile (iPhone SE)
  • 375px: Standard mobile (iPhone 12)
  • 768px: Tablet portrait
  • 1024px: Tablet landscape / Small laptop
  • 1366px: Standard laptop
  • 1920px: Desktop (Full HD)
Best Practices
  • Always test mobile sizes first (mobile-first approach)
  • Test both portrait and landscape orientations
  • Check sizes just above and below your breakpoints
  • Test on real devices when possible
  • Ensure touch targets are at least 44x44 pixels
  • Check that text remains readable at all sizes
Why Some Sites Don't Load

Some websites prevent being loaded in iframes for security reasons using the X-Frame-Options header or Content Security Policy.

If a site doesn't load:

  • Try the "Test HTML" tab with your own code
  • Use browser DevTools on the actual site
  • Check if the site allows iframe embedding