Octo Preview is a free Chrome extension developed by Andrew Levine. It falls under the category of Browsers and is specifically listed as an Add-ons & Tools subcategory.

This extension provides users with a live preview of markdown comments in pull requests (PRs) and issues on GitHub. As you type, Octo Preview automatically displays the rendered markdown output, allowing you to see how your comments will appear in real-time. This feature works anywhere on GitHub, including Gists.

It's worth noting that Octo Preview relies on making frequent HTTP requests to retrieve the parsed and rendered Markdown output from GitHub. As a result, it may not be suitable for users with slower internet connections.