CloneSpy is a fast and capable tool which can help you to find and remove duplicate files.

And while that's probably the program's most common application, it can also look for files which aren't quite identical. You can have it search for files which are the same name, say, or the same name and a similar size, or even just zero length files, whatever they happen to be named.

This is perhaps a little trickier than it should be, thanks to CloneSpy's less than intuitive interface. The program displays two "pools" where you can add folders, for instance; it can run in "Pool 1 only", "Pool 2 only" or "Both pools" mode; and you can make or add CSC (checksum) files. What does all this mean? We didn't know at first, either, so expect to spend a while browsing the Help file (itself fairly complex) before you properly understand what's going on.

Other elements of CloneSpy are fairly straightforward, though. You can have the program automatically delete duplicates according to your preferred rule (older, newer, small, larger, longer name, shorter name, more) just by selecting it from a list, for instance.

And in our tests the program seemed to find duplicate files extremely quickly, maybe faster than anything else we've used.

But please note, as ever with this kind of tool, treat it with extreme caution: used carelessly it can trash your system to the point that Windows won't start again. Don't use CloneSpy unless you fully understand what you're doing, and you've a full and recent backup to hand.

Version 3.3 brings (Changelog):

  • Added: The Main window is now resizable.
    Added: Added new search options to the Main window.
    Modified: Replaced some radio buttons with drop-down lists to make room for the new search options.
    Modified: The checksum database journal file is now kept permanently for performance reasons.
    Modified: Changed the order of buttons in several dialogs to be consistent with the standard button order in Windows.
    Modified: Moved all context help buttons from the window title bars to the lower right corner of the corresponding dialogs.
    Modified: The Size of main CloneSpy window option now only changes the Main window size at start-up (see Priority page of the Options window).
    Modified: In the default format for exporting lists of equal files, file time now appears before file path.
    Fixed: The Copy/Move Dialog Box on Windows 8 and higher is now suppressed.


CloneSpy is a powerful and extremely fast duplicate file finder. It's also a little complicated to use, so be careful - delete something important and you could easily trash your PC.