You can reformat your filenames to lowercase, uppercase, or propercase in an instant with this easy-to-use and effective file-renaming tool, although it may seem too expensive for its limited functionality. Lalim File Rename has a user-friendly interface that supports Windows drag-and-drop functionality. Just choose among the three file-renaming options, and Lalim File Rename swiftly renames the files. In our tests, we were also able to select a file from within a folder or choose all files to apply the renaming option. However, while similar applications allow you to add prefixes, suffixes, alphanumeric, and other file-naming conventions, this application only supports filename casing (lower, upper, and proper), which makes it a rather expensive renaming tool for a relatively simple functionality. Although novice users may find it handy, savvy and advanced users won't be impressed.
From Lalim Software:
With this utility you can change the filename case. You may change the filename to lower, upper, or proper case. It can automate thousands of file renames in a single click. You can drag-and-drop folder from Windows Explorer.