Markdown Outline for GitHub is a free Chrome add-on developed by mitsuruog. As the name suggests, this program allows users to easily view the outline of a markdown file on GitHub. With this add-on, users can quickly navigate through the different sections and headings of a markdown file, making it easier to find specific information. Additionally, Markdown Outline for GitHub also supports viewing the outline of markdown files on Gist, expanding its functionality beyond just GitHub. This add-on is a valuable tool for anyone who frequently works with markdown files, providing a convenient way to navigate and explore their contents.