The Side-by-side diff view in Github is a Chrome extension developed by smike. It falls under the category of Browsers and the subcategory of Add-ons & Tools. This extension adds the option to view diffs side-by-side in Github.

With this extension, you can transform the diff view on Github to a side-by-side view. Simply load a commit page and click the "Show Side-By-Side Diffs" button. The extension allows you to switch between side-by-side and unified diffs, making it easier to compare changes.

One of the advantages of this extension is that it displays previous comments, allowing you to view the context of the changes. Additionally, you can add new comments to any line, although they may appear distorted until you reload the page.