Clean Master is a powerful cleanup tool, a PC version of the popular Android app.

The program installs easily - no adware here - and is very straightforward to use. There's no complicated interface to browse, no settings to consider, not even a "Scan" button to hit: just launch Clean Master and it immediately begins checking your computer for Windows and application-related junk.

The scanning process is quick, taking less than 30 seconds on our test PC. Clean Master keeps you up-to-date as it works, too, displaying a running total of junk files and whatever it's checking right now.

Once the program has finished, it gives you a breakdown of the junk it's discovered, sorted in order of size. It told us our "System cache" was taking up 4.2 GB, for instance, and icons within that section gave us more details: "System Files" were consuming 2.5GB, "Temp Files" 948.9MB, "System Cache" 453.4MB, and so on.

We weren't sure what "System Files" were involved here, so clicked the icon and selected "Details" to find out more. The program listed crash dumps, installation files in our temporary folders, backup files of Windows Defender's database, all of which could safely be deleted.

Clean Master also wanted to delete some Windows Prefetch files, which we were less sure about, but that's not a problem. You can tell the program to ignore a particular class of files (Prefetch), or an entire category (System Files), and it won't scan or touch them again.

Elsewhere, we found the program detected browser caches, media player junk, other application-related leftovers (including from Windows 8 apps), even some redundant Registry keys. Each of these sections could also be manually checked to see and control exactly what the program is doing.

Once you've set up Clean Master - or just learned to trust it - clicking "Clean Now" wipes everything on the list.

The program can also be set up to run on boot, then check your system every 1, 2 or 3 days, 1 or 2 weeks, and alert you if the junk file total is more than some defined figure.