Responsive Viewer by Pixellize is a versatile Chrome extension designed for web developers and designers, allowing them to preview any website across multiple screen sizes simultaneously within a single tab. This tool is particularly useful for creating landing pages, testing client websites, or debugging layout issues. Users can see how their designs appear on various devices such as mobile phones, tablets, laptops, and desktops without needing to resize the browser window. The extension provides a clean, distraction-free interface that keeps all previews synchronized, making it easy to identify breakpoint issues quickly.

The extension features a tab-based organization system, enabling users to create multiple named tabs, each with a customized selection of screen sizes. Users can also define custom screen dimensions and utilize a built-in Live CSS Editor to inject custom styles in real time without reloading the page. Responsive Viewer effectively bypasses iframe restrictions, ensuring compatibility with most websites, while preserving zoom levels and custom settings across sessions.