Key Features:

• View your website on mobile, tablet, and desktop viewports side by side for faster responsive web design testing.
• Supports synced viewports for previewing webpages across common device sizes simultaneously.
• Allows adding custom viewport dimensions in pixels.
• Includes built-in presets for popular devices like iPhone, Android, iPad, tablets, laptops, desktops, and 4K screens.
• Offers options to switch between column and grid layouts.
• Enables rotation of individual viewports.
• Provides functionality to pin important viewports to the front.
• Allows expanding a single viewport for focused screen size inspection.
• Features synced scrolling and navigation/interaction across viewports.
• Supports switching between light and dark page themes where applicable.
• Enables saving and reusing viewport configurations for different websites.
• Includes a reset option to return to the default viewport setup.

Responsive Simulator is an essential tool for developers, designers, and QA teams to efficiently check responsive web design. It streamlines the process of testing breakpoints, comparing layouts, reviewing spacing, and identifying mobile navigation issues before deploying changes. By consolidating multiple viewport sizes into a single interface, it eliminates the need for numerous browser windows or constant DevTools resizing, making it easier to spot layout problems across different screen sizes quickly.

Common use cases include testing landing pages, checking responsive layouts during frontend development, reviewing client websites, QA testing, comparing navigation across devices, and testing custom breakpoints. This extension creates a local multi-viewport testing view within your browser without altering your website.

It is particularly useful for frontend developers, web designers, UI designers, QA testers, indie hackers, and users of Webflow, Framer, WordPress, Shopify, and custom site builders who need a quick and effective way to test responsive web design across multiple device viewports concurrently.