Editor’s note: The following review is part of Macworld’s GemFest 2012 series. Every weekday from mid June through mid August, the Macworld staff will use the Mac Gems blog to briefly cover a favorite free or low-cost program.
There are times when you need to find which of your files have changed in a folder full of sub-folders and files; this is especially useful for developers looking to see which files have changed in a project, or for web designers needing to find which files have been updated. With files, you may want to look at changes in source code, HTML code, or other data.
VisualDiffer ( Mac App Store link) is a simple, drag-and-drop tool that performs these comparisons and displays the results in a two-pane window, with one file or folder on each side. Drag a folder onto each side of the window and click on Show Diffs to find which files are different. You can check for differences by file content, by size, by timestamp and more. I tried a number of different folders, and comparing my iTunes Music folder with a backup, it took VisualDiffer about 30 seconds to scan some 65,000 files and find ones that had not yet been backed up.
A set of different colors will clue you in to folders that are different; you can then expand folders to see which files are not the same. You can delete any item, or copy them to the other folder. The program also offers a number of file exclusions; I chose to exclude certain types of music files when scanning my iTunes Music folder, for example. A web designer could choose to exclude HTML files if she is only looking at a folder of uploaded images. Or if you’re checking files on a network, you might want to exclude invisible .DS_Store files.
VisualDiffer also lets you compare files, such as backups. I found that the program couldn’t handle large files, such as two versions of my 110 MB iTunes Library.xml file; I had to force quit the program after several minutes. It was able to compare two backups of my blog’s database—a 37MB SQL file—though it took about 45 seconds to do so.
When comparing files, VisualDiffer uses the standard Unix diff command, and shows you each line that has differences. You can step through differences, or choose to only display differences, but you can’t make changes directly in the files, as you can with, say, BBEdit. This works on all types of files, but if you compare two Word files (for example), the extraneous data that is not text will make it hard to really compare them. Depending on what the file contains—whether it only contains text, or whether there are graphics, tables and charts—you may have some luck, but it’s best to use Word’s built-in comparison feature.
For developers and designers, or for anyone who needs to compare the contents of folders, VisualDiffer is a practical tool that will save time.