HTML Viewer for ChatGPT is a Chrome extension designed to enhance the experience of coding within the ChatGPT-4o with canvas interface. This tool allows users to visually preview or download their HTML and CSS code without the hassle of saving files locally. With a simple eyeball icon added to the canvas interface, users can instantly visualize their code in a pop-up iFrame, streamlining the editing process and making it more efficient.

The extension is straightforward to use; after generating or viewing canvas code in ChatGPT, the preview button appears for quick access. However, users should be aware of certain limitations, such as the requirement for code to start with a specific DOCTYPE and potential discrepancies in CSS rendering. Despite these caveats, the ability to download the code directly as an HTML file adds a layer of convenience for developers.