Viewport Resizer is a Chrome extension tailored for web developers and designers, facilitating the horizontal resizing of a website's viewport without altering the browser window size. This functionality is particularly useful for testing responsive designs and ensuring optimal viewing across various screen widths.

Key features include an intuitive resizable bar for easy adjustments, real-time display of the current viewport width in pixels, and a quick double-click option to expand to full width. Additionally, the extension remembers the last used width for each site, streamlining the testing process. Users can activate the tool with a single click and easily revert to standard browsing, enhancing efficiency during web development tasks.