What is Mobile-First?
It means designing for the smallest screen first and working upwards. Google's mobile-first indexing means your mobile experience directly impacts your search rankings.
Why do some sites fail to load?
Sites use X-Frame-Options or Content-Security-Policy headers to prevent iframe embedding. This is a security feature. Use this tool with your own local or staging URLs for best results.
Which devices are simulated?
iPhone SE, iPhone 14, Galaxy S23, Pixel 7, three iPad sizes, Galaxy Tab, and key CSS breakpoints (320px through 1920px). All based on real device viewport widths.
Is rotation accurate?
Yes — rotating swaps the width and height values to match how the browser actually reports dimensions in landscape mode, giving you a true viewport simulation.