Should I use mackeeper? Does it work?

1. No, you shouldn't.

2. No.

(125011)

Apple does not recommend it or not recommend it. We don't recommend it. You don't need it, and it would be a waste of money.

MacKeeper performs no useful function - Mac's don't need 'cleaning' - and, worse, is notorious for cluttering the Mac up with nag screens and adverts; it can be be extremely difficult to eradicate once installed. Avoid it as you would the bubonic plague.

Roger's note applies to any and all such apps. Do not ever install anything that claims to clean or speed up your Mac. Every one of them is totally useless and unnecessary.