Free RAM clean up app

I have used Memory Clean (Free) for years.

It's great at freeing up memory when memory hogs like Safari are going nuts because it can't handle a couple of tabs open at once.

Late 2012 Mac mini, macOS 10.13;  Watch S1, watchOS 4; iPad Air 2 & iPhone 6+, iOS 11.0.2; TV 4th Gen, tvOS 11;  Airport Express

RAM does not need cleaning. Any apps that pretend to "clean" RAM are neither necessary or recommended for Mac OS. What makes you think your RAM needs cleaning?

There are none, and they aren't needed. MacOS manages its own memory quite well.