Look up HTML reference is a free Chrome add-on designed for developers and web enthusiasts who need quick access to HTML documentation. This tool streamlines the process of looking up HTML elements, attributes, and ARIA-* attributes from reputable sources like WhatWG and MDN. Users can easily retrieve references and copy them in either markdown or HTML format, enhancing their workflow and productivity when coding.

This add-on is especially useful for those who regularly work with HTML, as it consolidates essential information in one place. While it covers a wide range of HTML elements and attributes, it's important to note that some attributes may not have associated references due to their absence on MDN. The developer intends to update the tool as new pages become available, ensuring users have access to the latest information.