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The Bulk Rename Utility is a neat little tool I found while searching for how to rename a bunch of files at once. I run a family gallery website on a four bay Synology NAS at home and it’s not a very powerful unit. I bought it primarily for the disk redundancy, but the memory is somewhat lacking. This isn’t an issue for viewing pictures, but I do run into problems when I’m uploading dozens of photos at once. I often get that dreaded fatal memory error and when this happens the NextGen Gallery plugin doesn’t always generate the thumbnails for each image.

I use a two pronged approach to creating and renaming these thumbnails in bulk. Since I need to resize the images first, I use Snagit to create the new thumbnails all at once. The problem I now face is that the thumbnails have the same exact name as the original file, whereas if the plugin had been able to do its job correctly, it would have created and renamed them appropriately. Snagit also capitalizes the extension too, so to manually update the name would be quite an arduous task. That’s where the Bulk Rename Utility comes to the rescue.

With this software I can remove or alter the filename, change the extension and case, add a prefix or suffix to existing filenames, and add numbers to files starting at whatever number I want. I can also preview what the end result will look like before making any actual changes. For my predicament, I need two things. First I need to add the “thumbs_” prefix to the files like NextGen, and then I need to change the case from upper to lower on all of the extensions.

The first time you open the Bulk Rename Utility, it looks like a lot to take in and a bit confusing, but it’s not that bad after taking a few minutes to read and figure out what each section does. I’ll include a sample of the changes I had to make accompanied by a screenshot to give you an example of how easy it can be to make bulk edits.


  1. Add the same prefix to all files in folder.
  2. Change case on all file extensions from upper to lower.


  1. Browse for the folder containing the files you want to change and click to highlight it.
  2. You should see the files show up in the large pane to the right. Highlight the files you want to change in this pane.
  3. Add the prefix “thumbs_” in the Add (7) section. You should now see the Add (7) title turn red.
  4. In the Extensions (11) section, select lower from the drop-down. The Extensions (11) title will also turn red.
  5. When you’re sure you’ve set all of your changes correctly, click Rename.

**You’ll notice after every setting you change, you’ll automatically get a preview of your new file name in the large top pane where your files are highlighted under the New Name heading.