Gmail HTML Editor is a Chrome extension developed by Brandon Fowler that allows users to easily edit emails they are composing in Gmail as HTML. With this extension, users can achieve a whole new level of customizability in their emails.

One of the main features of Gmail HTML Editor is the addition of a button to the Gmail "New Message" popup. This button enables users to switch from the default text editor to the HTML editor, giving them the ability to directly edit the email's HTML code. This is particularly useful for users who want to add custom formatting, styles, or other HTML elements to their emails.

Furthermore, the extension also works in the "mailto" screen, allowing users to edit emails as HTML when clicking on email links on websites or other applications. This ensures consistent editing capabilities across different platforms.

Gmail HTML Editor is a free extension and falls under the category of Browsers, specifically Add-ons & Tools. It provides a simple and straightforward solution for Gmail users who want more control over the appearance and customization of their emails.