Free tool, no sign-up. Preview any URL across every common Mac display size — MacBook Air 13", 15", MacBook Pro 14", 16", and the 27" Studio Display 5K, stacked, scaled, and labeled. Use it here or download the single HTML file and run it offline.
http://localhost:3000) at every Mac size at once.studiopractice.io/special-projects/macsim/.Best viewed on desktop — this tool previews sites at full Mac display sizes, which don't fit on a phone.
CyberRuler Once your design lands in the right size, measure it pixel-perfect on macOS. The Best Mac Ruler in the Galaxy. $9.99 one-time. See it →