No matter how big hard drives get, they always seem to fill up too quickly. This isn't due just to ever-increasing media file size; it also happens because the same files are often stored multiple times. When moving document folders around, downloading information, or making backups, it's easy to end up with many copies of the same file, sometimes with different names. Duplicate Cleaner Pro ($40, 15-day trial with limitations) is a utility that helps locate such files.

You can set Duplicate Cleaner to search specific directories, and filter types of files looked for, using either the preset file types, or your own, or simply "all files". You can compare contents to within a degree of similarity, with the default being 95%, and set upper and lower bounds of file sizes to be included. This last feature requires sizes be specified in kilobytes, making it slightly unwieldy to specify boundaries in today's more common megabytes or gigabytes.

The time it takes to search depends on the size of your hard disk and the narrowness of your filters, but if you have enough files to make a tool like Duplicate Cleaner worthwhile in the first place, it's probably a good idea to start the search in the evening and review the results in the morning. You can stop the process, but doing so will cause you to lose progress on the search and have to restart it. The results will be initially shown as groups of identical files, but it is also possible to sort them by path, name, or size, which can make finding the ones you most want to delete much easier. You can perform multiple selections on the list, open directories, or launch the files. There is also a second list of the folders which contain duplicate groups, so you can delete an entire redundant folder in one go.

Only rarely did Duplicate Cleaner not work as expected. It was not instantly clear how to restore groups after sorting by name. (You need to show the "Group" column, then sort by it.) I found it odd that you can't select more than one folder at a time from the folder listing. These are minor criticisms.

The trial/demo version of Duplicate Cleaner allows you to delete files in only the first hundred groups found, and does not allow you to load or save lists of duplicate files. The 15-day time limit should be sufficient to determine if Duplicate Cleaner will be useful to you.

At $40, Duplicate Cleaner is nearing the top of the cost curve for a single-function utility. However, it can be a tremendous help in cleaning the useless clutter from your hard disk, which consumes not only inexpensive disk space, but expensive time and attention as it bloats indexes and slows search results.

--Ian Harac