ScreenLab

Viewport resizer for responsive testing - view pages at different device sizes

Stop wondering if your site looks right. Know it does. Stop resizing your browser window over and over. ScreenLab lets you view any webpage across multiple device sizes simultaneously — no more guesswork, no more missed breakpoints. 🎯 One Click. Every Screen. Toggle ScreenLab and instantly see your site rendered across phones, tablets, and desktops side by side. Test responsive layouts in real-time without leaving your browser. 📱 Pixel-Perfect Device Presets iPhone, iPad, Android, MacBook, 4K monitors — all the devices your users actually use. Pre-configured viewport sizes so you can test what matters. ✨ Custom Viewports, Your Way Need a specific screen size? Create unlimited custom viewports. Save them for quick access across all your projects. 🔒 Lock Height Mode Keep all screens contained within your viewport, or unlock to see full-page scrolling behavior. You control the view. 🔄 Synchronized Scrolling Scroll once, scroll everywhere. All viewports stay perfectly in sync so you can compare sections across every breakpoint instantly. 📸 One-Click Screenshot Export Capture all viewports at once and download as a ZIP. Perfect for design reviews, client presentations, or QA documentation. 🌙 Dark Mode Built In Easy on the eyes during late-night debugging sessions. Toggle between light and dark themes instantly. ⚡ Works Everywhere Chrome, Firefox, Safari — ScreenLab runs on all major browsers. Test any website, any URL, any time. 💎 Free to Start. Pro When You're Ready. Test up to 3 screens free. Upgrade to Pro for unlimited viewports, custom presets, and screenshot exports.