Batch File Rename

Batch File Rename lets you pick many files at once, apply a naming rule, and download renamed copies bundled in one ZIP. It offers two rules: 'Common prefix + number' and 'Find & replace'. To be clear about what it does not do: a web page has no permission to rename files that already exist on your computer, so your originals are never touched. You receive a ZIP of copies with new names, which you can then unpack and use in place of the originals. Only file names change, never file contents.

How to use it

1. Click the dashed box 'Click to select multiple files (multi-select allowed)' and select several files in the picker, using Ctrl (Command on macOS) or Shift.
2. Under 'Rename method' choose a rule. 'Common prefix + number' turns each file into your prefix, a three-digit number and the original extension; type the prefix into 'Common prefix (a 3-digit number is added automatically)'. 'Find & replace' uses the 'Find text' and 'Replace with' fields.
3. Check the 'Preview rename results' list, which shows 'original → new name' for each file and updates as you type.
4. When it looks right, click 'Download N renamed files (ZIP)'. The button reads 'Zipping…' while working, and the browser then saves a file called renamed-files.zip.

A worked example, produced by the tool's own function

These results come from running the tool's rename function unchanged. Suppose you select six files in this order: IMG_2041.jpg, IMG_2042.jpg, notes.tar.gz, README, .gitignore and IMG_0001.JPG. In 'Common prefix + number' mode with the prefix 'trip_', you get trip_001.jpg, trip_002.jpg, trip_003.tar.gz, trip_004, trip_005 and trip_006.JPG. Numbers start at 001 in selection order and the extension is kept exactly (including its case). notes.tar.gz keeps its full double extension, while README and .gitignore have no recognised extension, so nothing is appended. In 'Find & replace' mode, finding 'IMG' and replacing it with 'photo' gives photo_2041.jpg, photo_2042.jpg, notes.tar.gz, README, .gitignore and photo_0001.JPG. Files that do not contain 'IMG' are unchanged.

Limits and known behavior

• Originals are never modified; you only get a ZIP of copies. Everything is zipped in browser memory, so selecting a very large total size can slow the page or make it fail, depending on your device.
• The number is always three digits, starts at 001 and follows the order in which you selected the files. You cannot set a start value, digit count or sort order. Past 999 files the number simply grows to four digits.
• 'Common prefix + number' discards the original name completely and keeps only the extension.
• The extension is everything after the last dot, except that double extensions starting with .tar (.tar.gz, .tar.bz2) are kept whole; dotfiles such as .gitignore are treated as having no extension. Other double extensions (such as .user.js) still keep only the last segment.
• 'Find & replace' only works on the part before the extension, is case-sensitive, does not support regular expressions, and replaces every occurrence in the name. If 'Find text' is empty the name stays unchanged.
• Duplicate new names are resolved automatically: in the preview and in the ZIP, a later file gets ' (2)', ' (3)' and so on (for example if two files both become b_1.txt, the second becomes b_1 (2).txt), so no file is overwritten or lost.
• If a new name contains a path separator such as /, the ZIP will contain a folder structure. Characters Windows disallows (: * ? " < > |) are not filtered out.
• The tool sees only file names, not folders, so same-named files from different folders cannot be told apart.

Why can't it rename my files in place?

A web page runs inside the browser's security sandbox. It can read the files you select but cannot rewrite or rename files on disk. So the tool reads each file, repackages it in memory under the new name, and lets you download the result. Your originals stay as they are.

Does the content of the files in the ZIP change?

No. Files are placed into the ZIP as they are; only the entry names differ. The modification time stored inside the ZIP is set by the zip library at packaging time, so it may no longer match the original file's modified date.

Which rule should I choose?

If the existing names carry no value, like phone-camera numbers such as IMG_2041.jpg, and you want a tidy sequence, use 'Common prefix + number'. If the names already have useful structure and you only want to swap one part, such as changing 'draft' to 'final', use 'Find & replace' so the rest of the information is preserved.

How do I delete a word from the names?

Put the word in 'Find text' and leave 'Replace with' empty. Every match is removed. For instance, replacing ' copy' (with the leading space) in 'report copy.docx' gives 'report.docx'. If you leave out the space in the search text, the space stays behind, so include it when needed.

Can I change the order of the files?

Numbers follow the order the browser reports for your selection, and the page has no drag-to-reorder control. If you need a specific order, sort the folder by name or date in your file picker before selecting all, or pick files one by one in the order you want. Different systems may report order differently, so rely on the preview list.

Privacy and processing

The whole process happens in your browser: reading the files, generating the new names and zipping them with a locally loaded library. The code contains no request that sends your files to a server, so they do not leave your device. The zip library is loaded on demand when you click download. Closing or refreshing the page clears the selected-file list.