CleanMyMac X

It helped me discover and erase the large chunk of data Bitcoin had left on my system.

[Edited by gentlesea, November 07]

It cleans Sketch app and Keynote cache files, as a designer I have GBs of cache. I really love that I can optimize my Mac in a click, that's super useful and fast.

It does the job a little too well. It messes up with the osx icon service, so finder just freezes, some icons disappear. The system becomes unusable unless you restart.

Scamware. It tastes as same as in Windows market: Auslogics BoostSpeed, IObit Advanced SystemCare, et cetera. Does more harm than good. Why pay yearly for something that you don't actually need, and if you insist you can do it for free? Modern operating systems are smart enough to self-clean.

They aren't open on how free their 'free download' is. They offer 500MB free cleaning then they want you to pay to further clean your craps.

1. Get CleanMe (FOSS). Or you can do this kind of stuff manually (search on the internet).
2. For Malware Removal module, get a specialized software that does that such as Malwarebytes (freemium).
3. For Privacy module, open System Preferences -> Security & Privacy -> Privacy tab.
4. For Login Items in Optimization module, open System Preferences -> Users & Groups -> Login Items tab.
5. For RAM Cleaner in Maintenance module, get Nektony Memory Cleaner (free). Users reported that the RAM cleaning by CMMX doesn't actually do anything.
6. For Uninstaller module, get AppCleaner (free) or Nektony App Cleaner & Uninstaller (freemium) for the best uninstallation results. Also you can do it manually by opening Finder -> type your software/company name on Search bar -> click on plus button (+) -> click 'Name' drop-down, click 'Other...', click on 'System files' (not the checkbox; it's for displaying it in the drop-down menu) -> click 'aren't included' drop-down, then click 'are included'.
7. For Updater module, just let your apps update by itself.
8. For Space Lens module, get GrandPerspective (FOSS), the one that looks like WinDirStat for Windows. If you want a visually pleasing app, get DaisyDisk ($10).
9. For Gemini (duplicate file finder) app, get dupeGuru (FOSS).

Probably the best Cleaning App for Mac.
Problem is, it has way too many features (which you'll probably won't need to use) and cleans too much things that you probably won't gain any benefit from doing so. Also it run in background whether you want it or not.
So overall, great product, but I would recommend getting a program that does less things (and doesn't run in background).

The app has the best design and performance. I really like it

One of the best programs of its kind