Bulk Rename Utility

About the Bulk Rename Utility

The Bulk Rename Utility is a free online tool that renames hundreds of files at once directly from your browser — no desktop software, installers, or command line required. Select a folder, choose a renaming action, preview every proposed name in real time, and apply the changes with a single click.
Unlike scripted mv loops or platform-specific rename utilities, this bulk rename tool shows you exactly what will change before it touches a single file, catches duplicate names automatically, and preserves file extensions so every renamed file stays associated with the correct application.

The tool uses the browser's File System Access API to read and rename files on your local disk. All logic runs client-side. File names, folder contents, and metadata never leave your device or touch a server.

Key Features

• Five Renaming Actions:
  Replace Text, Add Text, Numerate, Case Transformation, and Trim Text. Each action exposes controls tailored to its specific transformation, and you can chain actions by applying one, reviewing the result, and running another pass.
• Replace Text:
  Find a substring inside every selected file name and swap it for new text. Every occurrence is replaced — useful for removing unwanted prefixes like Copy of or standardizing separators.
• Add Text:
  Insert a string before or after the existing base name. Ideal for tagging files with project codes, client names, dates, or draft status.
• Numerate with Five Numbering Schemes:
  Add sequential identifiers using Arabic numbers (1, 2, 3), uppercase letters (A, B, C), lowercase letters (a, b, c), uppercase Roman numerals (I, II, III), or lowercase Roman numerals (i, ii, iii). Configure the starting value, delimiter, and whether the number appears before or after the name.
• Drag-and-Drop Reordering:
  While numerating, drag rows to reorder files so that sequential numbers follow your intended sequence. One-click sort shortcuts order files by name (natural sort), size, or extension, and reverse or shuffle the list in place.
• Case Transformation:
  Convert base names between ten case formats: lowercase, UPPERCASE, Title Case, kebab-case, snake_case, camelCase, PascalCase, space-separated, sentence case, and proper case.
• Trim Text:
  Strip a fixed number of characters from the start, the end, or both simultaneously. Extension-preserving, so .jpg and .pdf suffixes stay intact even when you trim aggressively.
• Extension Preservation:
  Every action splits the file name at the last period and applies transformations only to the base name. Extensions remain unchanged, so operating systems still recognize each file's type after the rename.
• Live Preview Table:
  See every original name next to its proposed new name in a sortable table. The preview recalculates instantly as you adjust settings, so there is no "dry run" step or hidden state.
• Selection Helpers:
  Beyond per-row checkboxes, a dropdown offers Select All, Select None, Invert Selection, and Select by File Type. The type submenu lists the five most common extensions in your folder — handy for renaming only the .jpg files inside a mixed directory.
• Duplicate Detection:
  The tool scans every proposed name for conflicts and disables the Rename button whenever two or more files would collide. An error panel lists each duplicate with the number of files that share it.
• OS Metadata Filter:
  Hidden system files — .DS_Store on macOS, Thumbs.db, desktop.ini, and ehthumbs.db on Windows, and .directory on KDE Linux — are skipped automatically so they never appear in the list or get renamed by accident.
• Client-Side Processing:
  All logic runs in your browser. File names and directory contents are never transmitted to any server, and the tool works offline after the page loads.

How Does the Bulk Rename Utility Work?

The tool uses the File System Access API, a modern browser feature that grants web pages controlled, user-permissioned access to the local file system. When you click Select Folder, the browser shows a native picker and — once you grant permission — returns a directory handle to the page. The tool iterates the handle's entries at the top level, filters out OS metadata files, and stores each remaining file with its handle, original name, size, and a selected flag.

For every rename action, the preview engine splits each file name into a base name and an extension at the last . character. Transformations apply only to the base name: Replace and Add use string operations, Numerate calls a formatter that produces numbers, letters, or Roman numerals, Case Transformation delegates to a shared case-conversion routine, and Trim uses string slicing with optional start and end offsets. The extension is then concatenated back on, so the file's type is always preserved.

When you click Rename Files, the tool iterates selected files whose new name differs from the original and calls FileSystemFileHandle.move() on each one. The browser writes the rename directly to your disk — there is no upload, no copy, and no temporary file. If any rename fails, the tool surfaces a toast with the error and stops.

How to Use the Bulk Rename Utility

1. Open the folder:
   Click Select Folder and pick the directory containing the files you want to rename. The tool lists every top-level file and omits hidden system metadata.
2. Pick a rename action:
   Use the action dropdown to choose Replace Text, Add Text, Numerate, Case Transformation, or Trim Text.
3. Configure the action:
   Fill in the inputs specific to your choice — for example, the find and replace strings for Replace Text, the starting value and delimiter for Numerate, or the target format for Case Transformation. The preview updates as you type.
4. Refine the selection (optional):
   Uncheck individual rows to exclude them, or open the selection menu to Select All, Select None, Invert Selection, or Select by file type.
5. Reorder rows for numerate (optional):
   When the Numerate action is active, drag rows to change the sequence or pick a sort option — by name, size, type, reverse, or random — from the sort menu.
6. Review the preview:
   Check each row in the preview table. Duplicates are highlighted and the Rename button stays disabled until every proposed name is unique.
7. Apply the rename:
   Click Rename Files. The browser writes each new name directly to your file system and a success toast confirms how many files changed.

Best Practices

• Back up before renaming:
  The tool does not copy files; it renames them in place and has no built-in undo. Make a folder copy first whenever the originals are hard to reproduce.
• Stack multiple passes:
  Complex transformations are easier to get right when you run several simple ones in sequence — for example, Case Transformation to normalize casing, then Replace Text to strip noise, then Numerate to add an index.
• Sort before you numerate:
  Sequential numbers follow the current row order. Sort by name, size, or type — or drag rows manually — before applying Numerate so the sequence matches your intent.
• Resolve duplicates quickly:
  If the duplicate warning appears, adjust the replacement text, starting number, or delimiter until every row is unique. The Rename button stays disabled until the conflict is cleared.
• Use Select by Type for mixed folders:
  When renaming only one category of file inside a mixed directory, open the selection menu and pick Select all X files rather than toggling each checkbox by hand.

Common Use Cases

• Photo organization:
  Rename sequences like IMG_0001.jpg to beach-trip-2026-01.jpg, beach-trip-2026-02.jpg, and so on by combining Replace Text, Add Text, and Numerate.
• Code file refactoring:
  Switch a folder of source files between naming conventions —userProfile.ts to user-profile.ts, or the reverse — without writing a shell script.
• Document cleanup:
  Trim auto-generated prefixes from downloaded invoices, normalize spaces and underscores across a batch of contracts, or add client codes as suffixes.
• Numbered deliverables:
  Produce ordered chapter files (I-intro.md, II-background.md, III-method.md) or lettered photo sets (A.jpg, B.jpg) using the Roman and alphabetic numbering schemes.
• Music and media libraries:
  Clean inconsistent track names by applying Title Case, replacing separators, and prepending track numbers — all without leaving the browser.

Frequently Asked Questions

Which browsers support the bulk rename utility?

The tool relies on the File System Access API, which is supported in Chromium-based browsers — Google Chrome, Microsoft Edge, Opera, Brave, and Arc. Firefox and Safari have not shipped the API yet, so the tool displays a fallback message when loaded in those browsers.

Are my files uploaded to a server?

No. The bulk rename tool reads and renames files directly through the browser's File System Access API. Every transformation runs client-side, and no file names, sizes, or contents are ever transmitted off your device.

Does the tool change file extensions?

No. Every action splits each file name at the last period and applies the transformation only to the base name. The extension is re-concatenated unchanged, so photo.JPG stays a .JPG file after a case conversion or a trim.

Can I undo a bulk rename operation?

The tool does not provide a built-in undo. Once files are renamed, the changes are written directly to disk by the browser. Review the preview table carefully and keep a backup of important folders before renaming.

Does it rename files in subfolders?

No. Only files at the top level of the selected folder are listed and renamed. Files inside subdirectories are ignored, and recursive renaming is not supported.

What happens if two files would end up with the same name?

The tool detects the conflict automatically, highlights each duplicated row, and disables the Rename button until every proposed name is unique. This prevents accidental overwrites before they reach your file system.

Why aren't .DS_Store and Thumbs.db in the list?

Those hidden OS metadata files — along with desktop.ini, ehthumbs.db, and .directory — are filtered out on purpose so that renaming a folder never touches files the operating system manages internally.

Related Tools

You might also find these tools useful:

• Duplicate File Finder — Scan a folder for byte-identical copies before renaming.
• Disk Space Analyzer — Visualize which folders and files consume the most space.
• Glob Pattern Tester — Prototype file-matching patterns like *.jpg or **/draft-*.md.
• Encrypt File — Encrypt renamed files with AES-256 before sharing or archiving.
• Word Counter — Count characters, words, and lines in text — useful when deciding how aggressively to trim long file names.