Outline HTML Elements is a Chrome extension developed by maxontech. This tool allows users to visually inspect website structures by outlining HTML elements with colorful borders, without affecting the layout. With the ability to press and hold a key-bind to display the outlines, users can easily debug CSS and understand webpage structures better.

Customizability is a key feature, as users can choose different outline colors for each HTML element and set their preferred key-bind in the extensions menu. Despite its powerful features, this extension remains lightweight and does not impact browser performance. Additionally, it is open-source, free to use, ad-free, and does not track user data.