Batch rename files

Find and replace on the name without its extension (plain text, or a regular expression with $1 groups; case-insensitive unless Match case is on), then change case (lowercase, UPPERCASE, Title Case), then the extension (keep, lowercase, UPPERCASE or change to another, typed with or without its dot; left empty, the extension is removed), then the New name pattern, if you give one ({name} is the name so far, {n} a number), then text added before and after, then numbering in list order (Start at and Step are whole numbers from -999,999,999 to 999,999,999, Step other than 0, and Digits a whole number from 0 to 12; a value outside these is said under the numbering fields, and Rename files stays off until it is changed; before or after the name, with a space, a hyphen, an underscore or a dot in between, or joined straight to it; when the New name holds {n}, the number goes there instead), then the file's modified date as a YYYY-MM-DD prefix. Nothing else changes a name: its own spaces stay as they are, at either end too, and the space or other separator of a number or a date only stands between it and a name, so a name the other rules left empty becomes the number or the date alone.

Type holiday-{n} as the New name. {n} becomes a number counted in list order with the numbering's Start at, Step and Digits (two digits by default: 01, 02, 03); add {name} to keep the old name as well, for example {name}-{n}. Choose Extension: lowercase to turn .JPG into .jpg. Without a New name, the numbering rule puts the number before or after the name with a space, a hyphen, an underscore, a dot or nothing in between.

Only when you use Open a folder to rename in place, which exists in Chrome and Edge on desktop (the File System Access API). The browser asks you to allow changes to that folder. Every file in the folder and its sub-folders is listed with its relative path; only the file name part is changed, so files stay in their folders. If files chosen another way join that list, the whole list is renamed as copies until they are removed again. Files chosen with Choose files, Choose a folder or dropped on the page are never changed on disk; you get a ZIP with the renamed copies instead, and, where the browser allows, the renamed copies as files of their own: through the share sheet where the browser can share these files (Safari on a Mac, iPhone, iPad, Chrome on Android; Save to Files keeps their new names), or one download each elsewhere (Firefox on a computer; the browser may ask once to allow several downloads). Only the files whose name changed are offered, and the originals stay where they are, for you to replace; if two renamed files of different folders end up with one name, only the ZIP, which keeps their folders, can hold them both. A new name that a browser may change as it saves a download (one that starts with a space, a dot or ~, holds two spaces in a row, a space other than an ordinary or an ideographic one, a % sign, or a control or invisible character, has a space after its last dot, or ends in .lnk, .url, .scf, .local or .desktop) leaves in the ZIP only, which keeps every name exactly. What the page offers is read from the browser itself, not guessed from its name. Folders with more than 20,000 files are refused; open a sub-folder instead.

After renaming in place, an Undo button restores the previous names until you rename in place again, open a folder or leave the page; moving or removing files in the list, changing the rules, adding files, Start again and a ZIP of other files leave it there, and so does a rename in place that is refused before any file moves. Swapping names (a to b and b to a) is handled safely through temporary names. Each new name is looked up just before its file is renamed: if another program has put a file there, the rename stops before that file, the files renamed until then keep their new names, the list shows each file under the name it has now, and Undo puts them back. A browser gives a page no way to rename a file only while its new name is free, so a file another program writes at that name in the instant between the look and the rename is replaced, and Undo cannot bring it back: leave the folder alone while the rename runs. Nothing is renamed while the preview shows a problem: an empty name, a character not allowed on Windows, a reserved name, two files that would get the same name, or a number the numbering cannot use.

They keep their folder and only the file name part changes, both when renaming in place and inside the ZIP. Two files in different folders may share a name; a conflict is only flagged when two files would end up with the same path. The ZIP holds every path exactly as the preview shows it, folder names included; a folder name a ZIP cannot hold as it is (with a control character or a backslash) is flagged on its row.

Yes, in the same way as the Create ZIP tool: deflate for files that shrink, stored as they are otherwise. The originals on your device are untouched.

Save a rule preset as JSON, then open it for another batch. Opening a preset never renames anything. Download the rename preview as CSV for review before applying the rules.

No. The page loads a small script into your browser and every operation runs on your device. You can check this yourself in the browser's network panel: after the page has loaded there are no upload requests. Closing the tab discards the file.

No. These basic tools are free and store nothing on our servers. The only limits are the tool's own: a folder opened for renaming in place holds up to 20,000 files (open a sub-folder for more); the ZIP of renamed copies holds up to 65,535 files of up to 4 GB each, and up to 4 GB in all once packed. Within them, the practical limit is your device's memory.

Nothing you open or type. While the tab is open, the tool pages keep a short list of the steps taken in it, in the tab's session storage: the step (page opened, started, succeeded, first success, used again or failed), the tool's name, the time, how many files were used and, for a failure, an error code; never a file name, the contents of a file or your text. It holds at most the latest 200 steps, and the browser deletes it when the tab closes. The page never sends it. Where a Report a problem button is shown, you can attach the last 20 steps to your report; nothing is attached unless you tick that box. In local storage the page keeps only choices you made: a Light or Dark theme until you choose System again, the language you picked with the EN / 中文 switch if it differs from your browser's language, and this tool in your recently used list if you switched that list on at the tools page.