Clean Disk is a simple utility for deleting unnecessary stuff from your drive. It frees up a little drive space, and more importantly it speeds up your browser and your OS when it’s starting to feel bogged down. It also shows you every file you have ever downloaded - even in private browsing mode - and allows you to delete this list that your OS keeps. It is not needed and better cleaned up from time to time. The other major feature that it has, is deleting all of the languages you don't use; you have tens of thousands of localization files inside Application bundles taking up space and counting as extra files, something that slows down backups as well as individual file counts, which can affect a lot of things in your OS experience.