MacKeeper by Kromtech is one of the most wide-spread and controversial optimisation and security applications for Mac OS. Currently it is considered legitimate and practicable program for performing Mac OS maintenance. However, due to questionable methods of distribution and obsessive behaviour when installed on Mac machines, it is determined by some reputable antivirus products as potentially unwanted application (PUA) or rogue program. For example, BitDefender Antivirus for Mac and Malwarebytes Anti-Malware for Mac detect and offer to remove MacKeeper on our test MacBook Pro. After installing MacKeeper starts showing alerts, reminders and warnings, claiming, that your Mac is “severely infected”, “has serious performance issues”, or “needs deep cleanup”. Annoying windows force some users to buy this application. The scale of the problems is exaggerated, MacKeeper is acting as “scareware”.