A SMALL TOOL FOR A REAL PROBLEM

Batch File Renamer

Turn messy filenames into a consistent set. Preview every new name, handle collisions and download a ZIP of renamed copies with unchanged file contents.

Browser processingNo account neededPreview before export

1. Choose files & naming rules

No files selected. A new selection replaces the current batch.

PrefixSuffix before extensionFind in filenameReplace withFilename letter caseExtensionNumberingNumber separatorStart numberIncrementNumber digitsNumbering order

Replace invalid portable-name characters Resolve collisions with -2, -3, … suffixes

Original files on your computer remain untouched. ZIP output is flat: folders are not retained. Limit: 100 files / 100 MiB total. Portable names use up to 240 UTF-8 bytes, avoid reserved Windows names, and compare collisions without letter case using Unicode NFC.

2. Check names & download copies

All naming conflicts must be resolved before downloading. The mapping lists original and new names. Web slug mode can remove non-ASCII letters; always review that preview. ZIP metadata may differ from the source files.

Ready. Try the example to see how it works.

Using Batch File Renamer

Create a predictable set of filenames with a before/after preview and a ZIP of renamed copies.

Choose files or try the sample text files. Each new selection replaces the current batch.
Set prefix, suffix, literal replacement, letter case and numbering. Preview names and resolve every reported error.
Download the renamed ZIP and optional mapping JSON. Your source files and their contents remain unchanged.

Example

Choose the sample text files, add project- as a prefix and keep three-digit numbering.
The preview shows filenames such as project-Notes 1-001.txt before packaging.

Questions & answers

Does this rename files on my computer?

No. It reads your selected files and creates renamed copies in a ZIP. It does not overwrite or move the originals.

Can I use it with any file type?

Yes. The tool does not decode file content or change formats. Extension changes affect only letter case; renaming a file is not format conversion.

How are duplicate names handled?

Collisions are checked without letter case after Unicode NFC normalization. Optional suffixes make names unique. Disable that option to report collisions instead.

Are folders preserved?

No. ZIP output is a flat batch using each selected file’s basename. Review possible collisions when files came from different folders.

What makes a filename portable?

The tool avoids common Windows-invalid characters, trailing dots/spaces and reserved device names, and limits names to 240 UTF-8 bytes. Filesystem rules can still differ.

What does web slug mode do?

It removes accents where possible, converts to lowercase ASCII words and joins them with hyphens. Non-ASCII letters may be removed; review the names carefully.

Are my files uploaded?

Reading and ZIP packaging happen locally in this browser. Files are not uploaded for processing. Website advertising and analytics follow the privacy policy.