Screen Sizer helps developers and QA engineers resize the browser window to mimic real device sizes and CSS breakpoints—no dev tools required.
• Built-in presets — iPhones, iPads, Pixels, Galaxy devices, laptops, desktops, and standard breakpoints • Custom presets — save your own widths and heights with a name • Favorites — star presets for one-click access • Quick resize — type any width × height and apply instantly • Import/Export — share preset JSON files with your team so everyone tests the same sizes • Current size — see the window dimensions at a glance • Dark/Light theme — follows your system or choose manually
Works in Chrome, Edge, and Firefox. All data stays in your browser; nothing is sent to any server.
