Responsive Design Tester
Free online responsive design tester, no installation required. Test pages in multiple device viewports
What is Responsive Design Testing?
Responsive design ensures websites work well across all devices and screen sizes. This tool lets you preview how your site appears on different viewports without needing physical devices. By testing at various breakpoints, you can identify layout issues, unreadable text, or broken components that only appear on specific screen sizes.
How to Use This Responsive Design Tester
Enter the URL of the website you want to test (it must allow iframe embedding for preview to work). Select a device preset (iPhone SE, iPhone 12 Pro, iPad, Desktop HD, etc.) to quickly set viewport dimensions. Or choose Custom to enter exact width and height. Toggle between portrait and landscape orientations. The preview updates in real-time. This helps catch responsive issues before users report them.
Common Viewport Breakpoints
Mobile: 320px-480px (small phones), 481px-767px (large phones). Tablet: 768px-1024px (iPads, tablets). Desktop: 1025px-1439px (laptops), 1440px+ (large desktops). Test your design at these breakpoints to ensure it adapts smoothly. Many frameworks use similar breakpoints (Tailwind: sm:640px, md:768px, lg:1024px, xl:1280px, 2xl:1536px).
▶Why does the preview show an error or blank page?
▶How accurate is this compared to real devices?
▶What's the difference between portrait and landscape?
▶Can I test my local development site?
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