best registry cleaner for the Mac

When asking which applications you need for registry cleaning or disk defragmentation, the answer is "none." OS X doesn't have registry, and the Heart of OS X which is based on FreeBSD also maintains itself very well. You do have Disk Defragmentations though, but they're very rarely necessary unless you do some seriously heavy audio or video editing. You do have programs like Cocktail which allows you to automatically schedule various tasks like log deletion, cache clearing and many others. It costs $14 for a single user license. Additionally, you have Onyx which is very similar in its functions, and similarly allows several tweaks to OS X which Cocktail also provides. Onyx, however, is free, though I personally prefer Cocktail because of its interface. You can use these two to compare, as one may have features lacking in the other application. You also have CleanMyMac" which is somewhat similar but this application focuses more on clearing out files, caches, languages and application-specific files which are left over from uninstalled programs. CleanMyMac cannot schedule, however. You can buy a single user license which works for six months which costs €14.95. A single user license without any limitations (a lifetime license) costs €29.95. You can try these three, since that is all that's mostly necessary as a registry doesn't exist.

From what I understand, a Mac does not have a registry, like Windows does. So, you don't need a registry cleaner.

Hmm but it is said that Onyx works only on OS X Snow Leopard