Oh My Star is described as 'provides a convenient way to manage your starred Github repositories. You can easily use Oh My Star to view, group, organize your GitHub Stars'. There are three alternatives to Oh My Star for a variety of platforms, including Online / Web-based, Windows, Chrome Web Store, Cloudron and Google Chrome. The best alternative is Astral, which is both free and Open Source. Other great apps like Oh My Star are Gitrep (Free) and GitHub Stars Tagger (Free).
Astral pulls down all of your starred repositories on GitHub and allows you to organize them using one or more tags. = Tags = Tags are the bread and butter of Astral. Simply add one or more tags to a repository, and keep them organized however you like.