Bulk File Renamer
Rename files in bulk with regex, sequence, and replace rules.
Chrome/Edge renames files locally. Other browsers get a ZIP save.
About
A browser-based bulk file renamer that lets you rename multiple files at once with five modes: find & replace, regex, sequential numbering, prefix/suffix, and case conversion. A real-time preview shows filenames before and after so you can verify changes before applying them.
Chrome/Edge use the File System Access API to rename files directly in local folders — no install, no server load. Firefox/Safari users can save a ZIP archive of the renamed files.
How to Use
Select Files
On Chrome/Edge, click "Select Folder" to pick a local folder directly. On other browsers, click "Select Files" to load individual files.
Set the Rules
Choose one of the five rename modes and configure the rule. The preview panel updates in real time with the before/after filenames.
Apply or Download ZIP
After reviewing the preview, click the action button. Chrome/Edge renames directly. Other browsers will download a ZIP — extract and replace the originals.
Glossary
- Bulk Rename
- The act of renaming multiple files at once in a single operation, saving the effort of manual, one-by-one changes.
- Regular Expression (Regex)
- A special notation for describing text patterns. For example, \d{8} matches any 8-digit number, enabling flexible find-and-replace operations.
- Sequential Numbering
- A method of adding sequential numbers (001, 002, 003…) to filenames. Useful for organizing photo collections.
- Prefix
- A string added to the beginning of a filename. Example: "2025_" → "2025_report.pdf"
- Suffix
- A string added to the end of a filename (before or after the extension). Example: "_final" → "report_final.pdf"
- File System Access API
- A web standard API available in Chrome/Edge that allows the browser to directly access the local file system with user permission.
- camelCase / snake_case / kebab-case
- Naming conventions for filenames and variables. Written as "myFileName", "my_file_name", and "my-file-name" respectively.
- ZIP Archive
- A compressed archive file containing multiple files. Used as the fallback output method in Firefox/Safari.
- Back-reference ($1, $2)
- A way to reuse captured regex groups in the replacement string. Example: pattern "(\d{4})-(\d{2})" → replacement "$2/$1" to swap date format.
- Extension
- The ".jpg", ".pdf", ".txt" suffix at the end of a filename. Changing the extension may prevent the file from opening correctly.
FAQ
- Q.Are my files sent to a server?
- No. All processing happens entirely within your browser. File contents and names are never transmitted anywhere.
- Q.Does it work on Firefox and Safari?
- Yes. On Firefox and Safari, select files with "Select Files" and save the renamed ZIP archive. Direct renaming requires Chrome or Edge.
- Q.Can I undo after a direct rename?
- No. Once applied, the rename cannot be undone automatically. Always verify filenames in the preview first. Use ZIP mode if you are unsure.
- Q.Can it handle thousands of files?
- Yes. Direct rename mode does not load file contents, so it handles thousands of files quickly. ZIP mode is recommended for under 1 GB total.
- Q.Do I need to know regex to use this?
- No. The Replace, Sequence, Prefix/Suffix, and Case modes require no regex knowledge. Regex mode is intended for intermediate and advanced users.
- Q.Can I change file extensions?
- Yes, but changing an extension may prevent the file from opening. When detected, a ⚠️ warning is shown in the preview panel.
Use Cases
📸 Organize Camera Photos
Bulk-rename "IMG_20250301_001.jpg" to "trip_kyoto_001.jpg" using Sequence mode.
💼 Standardize Business Documents
Batch-rename "report_2025.pdf" → "2025_report_v1.pdf" to match company naming conventions.
🎵 Sort Music / Video Files
Number album tracks sequentially and standardize them as "01_trackname.mp3".
💻 Unify Source Code Naming
Convert filenames from snake_case to kebab-case when migrating to a new project convention.