Though CCleaner is a paid program, it still has a completely free version which does not lack the most important features. It also offers a simple and user-friendly interface with big sized options. CCleaner is a lightweight optimisation software so there is no need to worry about the space it will take up. This is one of the most popular free junk cleaning software across all platforms - MacOS, Windows, and even Android. OnyX has in-depth maintenance tools as well as hidden settings. It also includes a bunch of macOS utilities like screen sharing, storage management, network diagnosis, and a lot more. Aside from its cleaning and maintenance abilities, OnyX has utility tools for building databases and indexes. It has an arsenal of rich selection of tools and commands. OnyX is from Titanium and it is one of the best free Mac Cleaner software out there.