FocusOn Renamer is a free program that allows you to rename files in batch as well as change extensions, case, and more.

With FocusOn, you can start with a folder name and optional template. Included templates are the original file name, the name without numbers, size, date, and much more. You can also click around on additional options including change case, extension, case sensitive, and a start and increment number. From there you can select add files or drag-and-drop them into the window.

You can preview the old image name and the new image name as you make changes, so you know you have it just the way you want. We tested it on about 15 photos, and the renaming process was instant.

FocusOn Renamer has no help, about or drop-down menus. That's because everything you need is laid out directly in front of you. Most of it is self-explanatory and what isn't you can test out without making any changes. If you need to rename a bunch of files, the FocusOn can get it done, with plenty of option, quickly and for free.