Quality Assurance Tool is a JavaScript utility designed for webpage quality assurance purposes. It focuses on measuring spacing and styles between elements on webpages. By holding down the Alt key on Windows or the ⌥ Option key on Mac, users can move the cursor and click to analyze the elements.

This tool simplifies the process by allowing users to hold down the Alt key and move the mouse cursor to an element to display its information. Similarly, clicking and moving the mouse cursor to another element while holding the Alt key provides detailed insights into the spacing and styles between elements.