Responsive Website Tester
Run this utility locally in your browser.
Run this utility locally in your browser.
Type a URL and the page loads it side by side at phone (375 x 667), tablet (768 x 1024) and laptop (1366 x 768) widths, scaled down so all three fit. It is a quick way to see how a layout reflows across breakpoints. Sites that forbid framing with X-Frame-Options or a CSP frame-ancestors rule will stay blank; for those, use the "open" links and your browser's device toolbar in developer tools.