Rename many files at once

How to use it

Drop the files onto the box (a whole folder works too, the tool walks inside it and picks up the files) or click to choose them. Then build the new name out of blocks: some fixed text, a counter, the name the file already has, the modification date. Blocks line up from left to right and move with Up and Down, so «holiday-» followed by a 3 digit counter gives holiday-001, holiday-002 and so on. The preview shows the old and the new name line by line before anything is downloaded, and if a file ended up there by mistake you drop it from the list with its own button.

The counter follows the order, and the order is not the one you expect

Numbering means lining up first and counting second, which is why the order is chosen here, between the order you added them, the name, the modification date and the size. Watch out for the way systems sort names: in plain alphabetical order IMG_10 comes before IMG_2, because characters are compared one by one and 1 comes before 2. Sorting by name here reads numbers as numbers (IMG_2, IMG_10), which is almost always what you want. It is also the reason the counter carries leading zeros: with 001, 002, 010 the alphabetical order and the numeric one finally agree, and the files stay in the right sequence wherever you open them.

The characters file systems refuse

Windows rejects \ / : * ? " < > | inside a name, and quietly trims trailing spaces and dots; on every system the slash is forbidden because it separates folders. The tool replaces those characters with a dash and tells you, instead of handing you a name the computer will refuse. Then there are the reserved DOS names Windows has carried around since 1981, that is CON, PRN, AUX, NUL, COM1-COM9 and LPT1-LPT9: a file called con.txt cannot be created, so in that case an underscore is added. Finally, repeated names block the download: inside a ZIP two entries with the same name overwrite each other without a word, and the check ignores letter case because for Windows and macOS Photo.jpg and photo.JPG are the same file.

Why you get a ZIP instead of the renamed files

A web page cannot write inside your folders, and browsers block dozens of downloads in a row. The only honest way to hand you fifty renamed files is to pack them, so the ZIP is built right here, byte by byte: for every file the CRC32 is computed (the check code the archive uses to notice a damaged byte) and its header is written, then the archive index goes at the end. Files go in without being compressed, the method the standard calls store: it is instant and, above all, the bytes stay identical to the original, which for already compressed photos and videos costs no space anyway. When there is a single file the ZIP is pointless and you get the file itself with the new name. Nothing leaves the device, there is no server behind this page.

The limits, stated up front

The date used is the file modification time, the only one the browser knows: it is not the shooting date written in the photo EXIF (the EXIF photo data tool covers that) and it is not the creation date. Keep in mind that copying files from a card or from a chat can turn that date into the day of the copy. The extension is never changed, at most it is lowercased, because renaming a .heic into .jpg converts nothing and the file stops opening; for double extensions like .tar.gz only the last part counts. The classic ZIP format used here goes up to 4 GB in total and 65,535 files, and the practical ceiling is 2,000 files at a time; past those numbers the tool stops and says so. There is no password protection and file permissions are not preserved.