De-Mainstream YouTube™ is a browser extension available on the Chrome platform. Developed by Mark M, this free add-on falls under the category of Browsers and belongs to the subcategory of Add-ons & Tools.

The purpose of De-Mainstream YouTube™ is to fix the YouTube™ algorithm by removing mainstream media results from searches. With this extension, users can have more control over the content they see on YouTube™. By clicking on the De-Mainstream popup next to the browser URL, users can select which channels they want to hide from their search results.

Once the channels are selected to be hidden, users can navigate to YouTube.com and perform a search. The channels that have been hidden will not be displayed in the search results. Additionally, users can right-click on a YouTube™ video in the search page and choose to "Block" or "Unblock" channels, allowing them to add their own custom channels to the block list.