Bad thing....I looked on the web and every place I looked to download that is sure to also add on some unwanted crapware or more serious malware, too.
If you look at the comments in the link below, especially the Linc Davis one, I think it will help you.
Any Mac App Store apps like CleanMyMac ? | Apple Support Communities
There is a similar program that is very popular on Windows....CCleaner. If you decide to try it, be sure to pay attention during install and UNcheck any offers of toolbars such as Google.
Piriform - CCleaner Mac