To further Pasquanel's comments, MacKeeper and other third-party utilities like CleanMyMac, most antivirus software, and others do far more harm than good. I personally do not recommend them.
There are a few great utilities, such as Malwarebytes Anti-Malware for Mac, Carbon Copy Cloner/SuperDuper!, DiskWarrior/Drive Genus/TechTool Pro, etc. They can be invaluable depending on the circumstances.
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