Batch File Renamer

About the Batch File Renamer

Give a whole batch of files new names in one go: number them, put the date in front, replace a word, clean up spaces and letter case, or change the extension. The preview shows every current and new name before anything happens, and warns about names that would clash or that Windows does not allow.

Then download the renamed copies as a ZIP (your originals stay as they are), or — in Chrome, Edge and Opera on a computer — rename the files in their folder, with undo while the page is open. The files are handled on your device and never uploaded.

How a new name is made

Each file’s name is taken without its extension and changed in this order:

1. Find and replace — plain text (every occurrence, matching case only if you tick it) or a regular expression, where the replacement can use $1, $2 … for the parts in brackets.
2. Letter case — lower case, UPPER CASE, Title Case or Sentence case.
3. The new-name template, where {name} stands for the result so far.
4. Spaces — kept, replaced with _, - or ., or removed.
5. The extension — kept, made lower or upper case, or changed (for example jpeg → jpg). Changing the extension renames the file; it does not convert it.

Placeholders

• {name} — the name after find & replace and letter case.
• {orig} — the original name, unchanged.
• {n} — a running number: choose where it starts, the step and the digits ({n:4} gives 0001 regardless), and the order — as listed, by name, oldest first or smallest first.
• {date} — the day the file was last modified, as 2026-01-31, 20260131, 31-01-2026 or with the time; {time} — the time alone, as 14-05-09. Dates use your device’s time zone.
• {folder} — the name of the folder the file is in.
• {ext} — the original extension (the new name keeps an extension anyway).

Renaming in place, safely

With Open a folder to rename in place… the browser asks for permission to edit that folder (File System Access API, in Chrome, Edge and Opera on a computer). The tool then never overwrites a file: a new name that another file already has is made unique or refused, and names that swap or move in a circle (a → b, b → a) go through a temporary name. Changes of letter case only (Photo.JPG → photo.jpg) also go through a temporary name, because Windows and macOS treat both spellings as the same file.

Where a browser can only copy files, a renamed file is copied under its new name, checked, and the original removed — its “modified” date then becomes today, and the tool says so. Undo the renaming puts the old names back while the page stays open.

Limitations

• Renaming in place needs Chrome, Edge or Opera on a computer. Other browsers — and phones — download the renamed copies as a ZIP, which holds less than 4 GB and up to 65,000 files.
• Up to 20,000 files at a time. Hidden files (names starting with a dot) are skipped.
• {date} is the date the file was last modified, not the date a photo was taken (which is stored inside the photo, in its EXIF data).
• Only file names change: folders are not renamed, and file contents are never converted.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.