Viewport Detector is a Chrome extension developed by Bootstrap Tools. It is a free tool designed specifically for Bootstrap 3 users. With the introduction of Bootstrap 3, each viewport is represented by a class name (col-lg-, col-md-, col-sm-, and col-xs-). This extension simplifies the process of switching between different viewports while resizing the browser, allowing users to easily determine which content should show on which device.

The main purpose of Viewport Detector is to assist developers and designers who work with Bootstrap 3. It provides a convenient way to preview how their content will appear on different devices. The extension is lightweight and easy to use, making it a valuable tool in the development process. While the current version offers basic functionality, the developer has plans to add more options in future updates.

Overall, Viewport Detector is a useful tool for anyone working with Bootstrap 3. It streamlines the process of testing content across different viewports, helping users make informed decisions about responsive design. With its simplicity and focus on Bootstrap, it serves as a valuable addition to any developer's toolbox.