Batch File Renamer

Batch File Renamer gives a whole set of files new names in one pass. Drop in a folder of photos called IMG_4821.JPG, IMG_4822.JPG and so on, a stack of scanned invoices, or a handful of exports with names like final_v2 (copy).pdf, set a few rules, and the list beside each file shows exactly what it will be called before anything is saved. Every new name is also an editable field, so the one file the rules get wrong can be fixed by hand without changing the rules for the rest.

There are four kinds of rule, and they always run in the same order: find and replace, then case, then numbering, then prefix and suffix. Find and replace works on plain text by default, so typing IMG_ and leaving the replacement empty deletes that text from every name. Switch on Regular expression and the find field becomes a JavaScript regex, with $1, $2 and so on in the replacement standing for captured groups, which is how IMG_(\d{4})(\d{2})(\d{2}) and $1-$2-$3 turn a camera's IMG_20240105 into 2024-01-05. Matching ignores upper and lower case unless Match case is on, and the extension is left alone unless Include extension is on, so replacing jpg cannot accidentally break .jpg. If the regular expression is not valid, the tool says so and why, and no name changes until it is fixed.

Case conversion turns names into lowercase, UPPERCASE, Title Case, or Sentence case, and the extension has its own setting, which is the quickest way to turn a camera's .JPG into .jpg without touching the rest of the name. Sequential numbering adds a counter before or after each name, or replaces the name with the counter entirely. You choose the starting number, the step, the separator, and the number of digits. Padding matters more than it looks: a list numbered 1, 2, 10 sorts as 1, 10, 2 in most file managers, while 001, 002, 010 sorts correctly, so the tool warns you when your last number needs more digits than you allowed. Numbers follow the list order, which can be the order you added the files, natural name order (where file2 comes before file10), or date modified, the right choice for photos from several cameras. The prefix and suffix are added last, so a prefix of Trip_ with numbering set to Replace name produces Trip_001.jpg, Trip_002.jpg, Trip_003.jpg.

Two files must never end up with the same name, because one would silently overwrite the other when you unpack the result. The tool checks every new name against all the others, ignoring case, since Photo.jpg and photo.jpg are the same file on Windows and on a standard Mac disk. The first file in the list keeps the name and each later one gets (1), (2), and so on before the extension, the same way the File Archiver on this site handles clashes. The row is outlined, says which name it will really be saved under, and the Clashes Resolved count shows how many there are. Characters that Windows does not allow in file names, such as a colon, a question mark, or a slash, are replaced with an underscore, and a rule that would leave nothing but the extension keeps the original name instead of producing a hidden file.

A web page cannot rename files on your disk in place. Browsers give a page a read-only copy of each file you choose, and no permission exists that would let it rename the original. So the renamed files come out as one ZIP, with each file saved under its new name, its modification date kept, and any sub-folders from a dropped folder kept as they were. Photos, videos, and other already compressed files are stored in the ZIP as they are, and text and documents are compressed. Unzip it where you want the renamed copies, and delete the originals once you have checked them.

Everything happens in your browser tab. The file names, the rules, and the file contents never leave your device, no request carries them anywhere, and the ZIP is built from the files on your own disk. That makes it safe for private photos, client documents, and anything else whose names you would rather not upload to a renaming service.