I'm Wilfredo. I designed on a 15-inch MacBook Air for years and kept getting bug reports from teammates about how things looked on their 14-inch Pros and 27-inch Studio Displays. Every responsive testing tool I tried was built around mobile breakpoints. This one isn't. It's just the Mac displays I actually work across, side by side, properly scaled, with the notch and menu bar where they should be. It's a single HTML file. No signup, no tracking, no build step. Click Download and it runs offline forever. Localhost works too, so you can preview your dev server at every Mac size before you ship. If you've ever pushed a layout and discovered the Studio Display version looks completely different from your laptop, this is for you. Free. Open to feedback on what's missing. More displays? Custom dimensions? Side-by-side compare with a reference URL?

Studio Practice

Preview any URL on every Mac screen at once

Preview any URL on every Mac screen at once